Materials Included In Kit

Additional Materials Required

Safety Precautions

Follow all normal laboratory guidelines. Remind students to wash their hands thoroughly with soap and water before leaving the laboratory. Please consult current Safety Data Sheets for additional safety, handling and disposal information.

Disposal

Please consult your current Flinn Scientific Catalog/Reference Manual for general guidelines and specific procedures, and review all federal, state and local regulations that may apply, before proceeding. All materials may be disposed of according to Flinn Suggested Disposal Method #26a or #26b.

Lab Hints

• Enough materials are provided in this kit for a class of 30 students working in pairs or for 15 groups of students. One additional large-sized sample of halite (Mineral 5) is provided, as this is the mineral suggested for use in the cleavage test (Test 5)—use one halite sample as part of the teacher display set and the other for the cleavage test.
• The minerals in this kit can be saved and used to repeat the lab for additional classes. Extra halite and calcite testing chips, sold in packages of 15, are available separately (as these are the minerals that will dissolve—see solubility test results for details).
• Activity 1 is designed to engage students in an investigation in which they collect evidence and observations for eight different tests on eight different minerals. At the start of the investigation, each mineral is identified with only a number. At the conclusion of the lab, the students use the evidence gathered to determine the name of each mineral by comparing their data with known properties of minerals. A reproducible handout of known properties is provided as a PDF.
• The minerals for Activity 1 have been carefully chosen so that each sample has one very unique property. The mineral selection process used should assure your students a great deal of success.
• A suggested timeline for this laboratory activity is provided below. The idea is to spread the lab out over a week-long unit on minerals, with some class discussion and some lab time each day. Your actual timeline may vary depending on time constraints.

Suggested Timeline: (45–50 minutes per day)

• Day 1—Introduction to minerals; Test 1 Observations; Guess Who activator
• Day 2—Test 2 Light Interaction; Test 3 Streak; Test 8 Set up Solubility
• Day 3—Test 4 Hardness; Test 5 Cleavage; Test 6 Smell
• Day 4—Test 7 Ice; Finish observations on Test 8 Solubility Day 5—Perform Activity 2

Teacher Tips

• Prior to Testing—Hand out the mineral testing chips and have students place each mineral next to the corresponding number on their evidence/observation table based on the descriptions given.
• Test 1: Observations—Encourage students to use the magnifying glasses. Remind students to take precise notes and make very careful observations.
• Test 2: Light Interaction—This is a good opportunity for students to learn some new vocabulary. Of the three transparent minerals, only the calcite (Iceland spar) displays double refraction. To see this property lay the mineral over a thin line on the paper, and then slowly rotate the mineral.
• Test 3: Streak—Remind the students not to color the streak plates. Only one or two “streaks” are necessary. Students will struggle with the distinction between clear and white streaks. There is not a definite right or wrong answer; have students record whichever they think is appropriate.
• Test 4: Hardness—This is possibly the hardest test (no pun intended) and will require the most time. There is a great deal of logic involved in arriving at a hardness value for each sample. Many minerals vary a bit in hardness, so it is not always possible to get a “right” answer. Students should be as precise as possible. Encourage them to start with finding a range. For example, determine which minerals scratch the nail and which can be scratched by the nail. This will immediately separate the minerals into those with hardness greater than 5 and less than 5. Repeat this logic for all the other tools provided—penny, fingernail, streak plate. (Note: A good discrepant event to capture the students’ interest is to ask them to predict what will happen if a steel nail is “scratched” across the overhead projector. After they have given their dire predictions, rub the nail provided in the kit back and forth on the overhead. The steel nail will not scratch the glass since it has a hardness of 5 and the glass has a hardness of 6.
• Test 5: Cleavage—This test is done as a teacher demonstration to avoid destroying all of the minerals in the kit. The demonstration is dramatic if done on the overhead projector. Carefully tap a nail into one of the large halite teacher samples (Mineral 5) provided. After a few firm taps, the mineral will “cleave” along a perfectly flat surface. This sample has perfect cleavage. Tell the students that all of their samples have already been broken from larger pieces, so cleavage of any other samples is not necessary. Students should examine the surface of each mineral and classify the type of cleavage observed.
• Test 6: Smell—This test can be somewhat misleading because sometimes students smell things left on the streak plate from prior tests. Many of the minerals do have strange smells; however, sulfur smells extremely bad—like rotten eggs. This is another test that does not have a “right” answer. Ask the students to record their own observations.
• Test 7: Ice—The rate of melting is controlled by a number of factors. Conductivity, specific heat, and the mass of the sample all affect the rate of melting. The halite will stand out since it begins to dissolve into the ice cube. Ice cubes from standard ice cube trays can be used, or small paper cups can be filled half way with water and frozen. The cups work nicely since they also keep the minerals from falling off.
• Test 8: Solubility—This is a dramatic test because the halite (Mineral 5) and calcite (Mineral 4) both will dissolve and disappear after a few days in the vinegar. It may be necessary to change the vinegar after a day if some of the calcite remains. Students should also be encouraged to observe the samples carefully. There should be small bubbles coming from the calcite, but not from the halite. When testing solubility in water only the halite will dissolve. This test may take a few days. Materials have been included in the kit to test one set of minerals for the entire class. If the kit will be used year after year, replacement halite and calcite testing chips, as well as additional vinegar, will be needed and are available from Flinn Scientific—Halite chips, 15 (AP6095); Calcite chips, 15 (AP6096); Vinegar, 4-L (V0005).
• Mineral Identification—After all the evidence has been gathered, hand out the reproducible table of known mineral properties provided on page 16 or have the students use a table provided in their books. Many of the students will have conflicting evidence recorded in their data table. This may actually be good. Students need to learn to deal with real data, and construct their hypotheses based on all the evidence gathered. Students will see that after evaluating all the data against the known properties, each mineral sample has at least one key characteristic property.
• An excellent follow-up demonstration to Activity 2 is Flinn Scientific’s Upset Tummy—MOM to the Rescue Demonstration Kit, AP5934.
• Have students further investigate the minerals and rocks listed in the background section and other rocks and minerals that are commonly used.

Further Extensions

Alignment with AP^® Environmental Science Topics and Scoring Components

Topic: Land and Water Use. Mining (Mineral formation; extraction; global reserves; relevant laws and treaties).
Scoring Component: 5-Land Use, Mining.

Sample Data

Activity 1

Activity 2. Rocks and Stomach Acid

Answers to Questions

Activity 1

1. Which of the minerals might be used for the panes of windows? What other tests should be performed to determine if the mineral(s) could be used for windows?

   Mica in the past was used for windows in ovens. Halite is a clear mineral and could be used but would dissolve in the rain. Calcite is also a clear mineral and would make interesting double refractive windows.

2. Some of the minerals had white streaks; some had clear streaks. How could this test be changed to tell the difference between minerals with white streaks and minerals with clear streaks?

   Use a black streak plate instead of a white one.

3. Some minerals are so hard that they won’t crush into a powder when rubbed on a ceramic streak plate (tile). Did any of the minerals seem to scratch the streak plate instead of being crushed? Which? Why did the minerals do this?

   Quartz (Mineral 8) will sometimes scratch the streak plate instead of being crushed. It will do this because quartz and the ceramic streak plates have the same hardness.

4. What common minerals may scratch the ceramic streak plate (tile)?

   Diamonds or any minerals with a hardness greater than 7.

5. Sometimes pieces of minerals are added to different kinds of soap to make the soap gritty so it can scrub off really tough dirt or scum. The idea is that the gritty mineral will scrub off the scum, without scratching the surface being cleaned. Would it be a good idea to put pieces of quartz into soap used to clean glass? Explain.

   Since quartz has a hardness of 7 and glass has a hardness 6, this would not be a good thing. The soap with the quartz would scratch the glass instead of clean it!

6. Most beaches are made of quartz. When rocks weather, most of the other minerals wear away, but the quartz is left behind. Why is the quartz left behind after all the other minerals are worn away?

   Soft minerals such as mica and calcite get worn away, while harder minerals such as quartz do not get worn away. When many igneous rocks weather, the last remaining mineral is quartz. Therefore, many beaches are made of quartz sand.

7. Many very expensive saw blades are coated with diamonds. Diamond-covered saw blades can cut right through metal, rocks, even concrete! Why are diamonds so good at cutting almost everything?

   Diamonds are good for cutting because they have a hardness of 10 and can scratch and cut almost any material on Earth.

8. Jewelers sometimes use their knowledge about cleavage to split large gemstones into smaller ones. Which minerals tested in this lab could easily be split into smaller pieces with the same or similar shape as the original mineral?

   Calcite and halite could definitely be cleaved into smaller crystals with similar shapes. (Note: Diamonds are also cut from larger pieces.)

9. Have you ever smelled anything similar to the smells produced by any of the minerals? If something smells similar, it is probably because the chemical compositions are similar. The atoms that make up the mineral are probably the same atoms that make up the object that smells the same! p>Yes, sulfur is a mineral that smells like rotten eggs.
10. Things that smell a lot usually have very loosely bonded atoms. Which mineral smelled the most? Which mineral was the softest? Which mineral probably has the most loosely bonded atoms?

    Sulfur smells bad and also has a very low hardness. Sulfur most likely has the most loosely bonded atoms.

11. What will go through an ice cube faster, a big piece of mineral or a small piece?

    Big minerals hold more heat energy compared to small minerals and should melt the ice faster.

12. Companies mine thousands of tons of one of these minerals each year to melt snow and ice on roads. Which mineral is it? Explain.

    Halite or salt is used in many northern cities to melt ice in the winter. The halite melted the ice very fast in the ice test.

Activity 2

1. Did the pH of the vinegar solution change after the limestone was added? Explain what caused the pH change.

   The pH paper indicates that the acid was neutralized by the limestone, reducing the acidity of the vinegar solution.

2. How does this activity compare to the use of calcium carbonate antacid products to relieve upset stomachs?

   This activity shows the same effects of antacids—the neutralization of stomach acid.

3. Some buildings and statues are made with limestone. Would you like to live in a house made of limestone if the house was in an area that received a lot of acid rain?

   Many buildings and statues made of limestone are being devastated by acid rain. The solubility test showed that mineral 4 is soluble in acid. Granite is a much better building material.

4. Acid rain can poison lakes. This can be prevented by adding limestone to the lake to neutralize the acid. Would water, with limestone dissolved in it, have a pH above or below 7? Why?

   Water with limestone dissolved in it has a pH above 7. This could be inferred because the limestone reacted with the acid to produce carbon dioxide gas (bubbles).

Teacher Handouts

13549_Teacher1.pdf

References

Rock and Mineral Uses, www.rockandminerals.com/uses/htm (accessed June 2006)

Introduction

Have you ever used a rock or mineral? The answer is an emphatic YES! The byproducts of rocks and minerals are all around us. Explore the properties of several rocks and minerals in the following activities.

Concepts

• Minerals
• Rocks
• Metals
• Ores

Background

Many of the items used in our homes and in industry are made of materials that were mined from the ground. Unfortunately, people seldom stop to think about them. There are thousands of known rocks and minerals. Based on current consumption rates, it is estimated that every person in the United States will use more than a million pounds of rocks, minerals and metals during their lifetime including:

• 800 pounds of lead
• 750 pounds of zinc
• 1,500 pounds of copper
• 3,600 pounds of aluminum
• 32,000 pounds of iron
• 27,000 pounds of clays
• 28,000 pounds of salt
• 1,000,000 pounds of stone, sand, gravel and cement

The following is a list of a few rocks and minerals and how they are commonly used:

Aluminum
Aluminum is the most abundant metal element in Earth’s crust. It is used in making cans and other containers, in the manufacturing of lightweight parts for automobiles and airplanes, in building construction, and in almost every modern appliance found in the home. It is also the active ingredient in many underarm deodorants.

Antimony
Antimony is extracted from stibnite and other minerals. It is used as a hardening alloy for lead, especially in the manufacture of storage batteries. It is also used in solder, collapsible tubes and foil, sheet and pipes, in semiconductor technology and in fireworks. Antimony salts are used in the rubber and textile industries, in medicines and glassmaking.

Bauxite
Bauxite is the mineral ore of aluminum which is used in the manufacture of cans, airplanes, sporting and electronic equipment and home appliances. Most of the bauxite used in the United States is imported from Australia and Jamaica.

Barium
Barium is used as a heavy additive in oil well drilling mud, in the paper and rubber industries, as a filler or extender in cloth, ink and plastic products, in radiography, as a deoxidizer for copper, in sparkplug alloys and in making an expensive white pigment.

Beryllium
Beryllium is used in the nuclear industry and in the manufacture of lightweight, very strong alloys used in the aircraft industry. Beryllium salts are used in fluorescent lamps, in X-ray tubes and as a deoxidizer in bronze metallurgy. Emerald and aquamarine are “beryl” gemstones.

Calcite
Calcite is a mineral consisting largely of calcium carbonate and is the second most abundant mineral on Earth. Calcite uses include animal feed, antacids, chemical industry, dough strengthener, decorative stone in buildings, building construction, filler in baking powder, glass industry, manufacturing of paper, optical purposes, photography, statues and waste treatment.

Chromite
Chromite is a mineral ore of chromium which is used in making steel, “chromed” parts for automobiles and appliances and in the manufacturing of chromic acid which is used to tan much of the leather used in making shoes, belts, purses, jackets, gloves, etc.

Coal
Coal is primarily used in the generation of electricity. About 56% of all the electricity used in the United States is produced from coal-fired facilities. The rest of our electricity is produced from nuclear power plants (24%), natural gas power plants (10%), hydroelectric resources (8%) and alternative sources (e.g., wind, solar)—about 2%. Coal is also a source of raw material for making heating oils, chemicals and medicines. At current rates of use and under current environmental regulation, about a 300- to 400-year supply of coal remains. To put that in perspective, the first English settlement in the New World was at Jamestown, VA in 1607—just about 400 years ago.

Cobalt
Cobalt is used in making superalloys for jet engines, chemicals (paint dryers, catalysts, magnetic coatings), permanent magnets, and cemented carbides for cutting tools. The United States uses about one-third of the world’s production of cobalt.

Copper
Azurite, chalcopyrite, and malachite are ores of copper which are used in the manufacturing of brass, bronze, coins, jewelry, cooking utensils and pigments. Most of the wiring in electrical appliances, TVs, stereos, computers, telephones, aircraft, satellites, automobiles, residential wiring, plumbing, etc. is also made from copper. Malachite also provides shades of green used in making cosmetics and was used by earlier people for making paint used on their clothing, faces and cave walls.

Feldspar
Feldspar is a rock-forming mineral. It is important industrially in making glass, ceramics, enamelware and soaps. It is also used in making bonding material for abrasive wheels, cements, fertilizer, tarred roofing materials and as a sizing or filler in textiles and paper.

Flint
Flint was very important to civilization from its early use in the Stone Age until the mid-1800s. It was used extensively by earlier people in making arrowheads, spearpoints, knives, and other scraping and cutting tools. It was also used—with steel—as a primary way to start a fire until the invention of matches in the early 1800s, and it was widely used as the ignition system for flintlock rifles until the mid-1800s.

Fluorite
Fluorite is used in the production of hydrofluoric acid and the source of the “fluoride” in toothpaste. It is used in the pottery, ceramics, optical, electroplating and plastics industries; in the metallurgical treatment of bauxite to make aluminum; as a flux to remove impurities in open hearth steel furnaces and in metal smelting; in carbon electrodes, emery wheels, electric arc welders and as paint pigment.

Galena
This ore—lead sulfide (PbS)—is the primary source of lead used in the manufacturing of batteries. Lead is used as an effective sound barrier and to shield us from harmful radiation in airplanes and from X-rays used in medical or dental offices. It is also used in making wheel and fishing weights.

Gold
Gold is used in dentistry and medicine; in jewelry and art; in medallions and coins; and in ingots as a store of value by banks throughout the world. Because of its malleability (gold wire can be thinner than a human hair) it is used in intricate circuitry for scientific and electronic instruments such as computers. It is also used in the electroplating industry.

Gypsum
One of gypsum’s primary uses is in the manufacture of “sheetrock” or wallboard. The walls in homes, offices and schools are usually at least partly constructed using a gypsum board.

Halite (Salt)
Commonly recognized as salt, halite is used in human and animal diet, food seasoning and food preservation. It is used to make sodium hydroxide, soda ash, caustic soda, hydrochloric acid, chlorine and metallic sodium, in ceramic glazes, metallurgy, the curing of hides, in mineral waters, soap, home water softeners, as a highway de-icer, in photography and in optical parts of scientific equipment. Single crystals can be used for spectroscopy, ultraviolet and infrared transmission.

Hematite
A primary ore of iron. Hematite is processed to produce iron which is used to make steel which, in turn, is used in everything from automobiles to flatware to the machinery used to make almost everything else. Many different minerals can be combined with iron in producing steel. Each provides a different set of valuable properties to the finished product. A familiar example is stainless steel. Steel is used in the manufacture of such things as kitchen appliances, furniture, tools, bridges, buildings, automobiles, construction equipment, manufacturing machinery, highway construction, shipbuilding, trains, railroads, etc. Powdered iron is used in magnets, high-frequency cores, auto parts, and as a catalyst. Radioactive iron (iron 59) is used in medicine and as a tracer element in biochemical and metallurgical research. Iron blue is used in paints, printing inks, plastics, cosmetics, paper dyeing. Black iron oxide is used as a pigment and in polishing compounds, medicines and magnetic inks. The other primary ore of iron is magnetite.

Limestone
Limestone is used as dimension stone in buildings and as a component of cement used in the construction of everything from homes and sidewalks to bridges and skyscrapers. It is composed primarily of calcium carbonate, the primary ingredient in such things as antacid tablets and liquids for an upset stomach.

Magnetite
An ore of iron which is used in making steel, nails, kitchen appliances, furniture, tools, bridges, buildings, automobiles, construction equipment, manufacturing machinery, highway construction, shipbuilding, trains, railroads etc. Powdered iron is used in magnets; high-frequency cores; auto parts; and as a catalyst. Radioactive iron (iron 59) is used in medicine and as a tracer element in biochemical and metallurgical research. Iron blue is used in paints, printing inks, plastics, cosmetics and paper dyeing. Black iron oxide is used as a pigment and in polishing compounds, medicines and magnetic inks. Also see hematite.

Marble
Marble is used as dimension stone in building construction and for making decorative items (e.g., pillars, floor and bath tiles, tabletops).

Mica
Micas commonly occur as flakes, scales or shreds. Sheet muscovite (white) mica is used in the manufacturing of electronic insulators. Ground mica is added to paints and cosmetics to add “sparkle,” in joint cement, as a dusting agent, in well-drilling muds as well as in plastics, composition roofing, rubber and welding rods.

Molybdenite
Molybdenite is an ore of molybdenum which is alloyed with steel and other metals to improve hardness, strength and resistance to abrasion and corrosion. It is used in the manufacturing of jet engines, in oil refining, in lubricants and as pigmentation in dyes, inks and paint. As a pure metal, molybdenum is used as filament supports in lightbulbs because of its high melting point—4,730 °F—in metalworking dies and furnace parts.

Platinum Group Metals
The platinum group metals (PGM) include platinum, palladium, rhodium, iridium, osmium and ruthenium. They commonly occur together in nature. Platinum is used principally in catalytic converters for the control of automobile and industrial plant emissions but is also used in making jewelry. PGM metals are also used in catalysts to produce acids, organic chemicals and pharmaceuticals as well as in bushings for making glass fibers used in fiber-reinforced plastic, in electrical contacts, in capacitors and in resistive films used in electronic circuits. They are also used in dental alloys for making crowns and bridges.

Phosphate
Phosphate rock is used to produce phosphoric acid for ammoniated phosphate fertilizers, feed additives for livestock, elemental phosphorus, and a variety of phosphate chemicals for industrial and home consumers. Phosphorous is a very important nutrient for the human body. It is the basic building block for DNA and RNA and is essential for bone and teeth growth. Phosphoric acid also helps provide the “tingly” taste experienced when drinking many soft drinks.

Potash
Potash is a carbonate of potassium used as a fertilizer, in medicines, in the chemical industry and to produce decorative color effects on brass, bronze and nickel.

Pyrite
Pyrite (also known as fool’s gold) is used in the manufacture of sulfur, sulfuric acid and sulfur dioxide. Pellets of pressed pyrite dust are used in the recovery process of iron, gold, copper, cobalt and nickel. It is also used to make inexpensive jewelry.

Quartz
Quartz is used in laboratory tubes, crucibles, glass, digital watches, radios, TVs, radar, sandpaper and in construction molds and foundry molds. It is also used in jewelry and other gem uses.

Silica
Silica is most often used in the form of an anti-caking agent in foods (e.g., milk, chocolate, sweeteners). For example, those little packets of sweetener used for coffee instead of sugar are as much as 95% silica sand—ground so finely that it will dissolve. Silica is also used in the manufacturing of computer chips, glass and refractory materials, ceramics, abrasives, water filtration processes, as a component of hydraulic cements, as a flatting agent in paints and as a thermal insulator. It is also used as a filler in the making of paper.

Silver
Silver is used in chemistry, jewelry, in electronics because of its very high conductivity and as currency in the form of coins—usually as an alloy. Other uses included the lining of vats and other equipment for use as chemical reaction vessels and in water distillation processes. It is also used as a catalyst in the manufacturing of ethylene, in making mirrors, as plating for flatware, dishes and tea sets and in dental, medical and scientific equipment.

Soda Ash
Soda ash and trona (see “trona”) are both sodium carbonate. Soda ash is used in the manufacturing of glass containers, fiberglass, specialty glass and flat glass. It is also used in the paper-making process, in liquid detergents, in medicine, as a food additive and in cleaning compounds.

Sulfur
Sulfur is used in the manufacture of fertilizer (necessary to grow our food), chemicals, in the manufacture of sulfuric acid, in papermaking, film, tires, paint, detergents, explosives, matches, drugs and dyes.

Titanium
As a metal, because of its light weight, strength and heat resistance, titanium is primarily used in the manufacture of such items as jet engines, aircraft frames and space and missile components. Titanium is most commonly seen as titanium dioxide. Titanium dioxide has thousands of applications as a “whitener” in items such as paint, in food items such as sugar and candy and in toothpaste.

Trona
Trona is a primary source of sodium carbonate. It is used in the making of toothpaste, in glass and papermaking, in soaps and detergents, in the treatment of water for domestic use and in the manufacture of a number of chemicals. One of its most important applications is its use in baking soda and baking powder, a necessary ingredient in making bread, cookies, cakes, etc.

Tungsten
Tungsten is used in steel making and thus in all the items constructed of steel that require the hardness and other characteristics provided by tungsten-steel alloys. It is applied on metalworking, construction and electrical equipment; in transportation equipment, as filaments in lightbulbs and as components of dyes, enamels and paints and for coloring glass.

Zinc
“Copper” pennies are actually mostly zinc. One of the primary uses of zinc is as a protective coating on steel used to manufacture things such as automobile frames and bumpers to prevent corrosion and oxidation (rusting). It is also used as an alloy metal with copper to make brass, and for “galvanizing” iron used in making nails and roofing material that will not corrode when exposed to the weather.

Experiment Overview

In this experiment, minerals will be tested and identified and the effects of rocks on stomach acid will be explored.

Materials

Safety Precautions

Follow all normal laboratory guidelines. Wear safety glasses. Wash hands thoroughly with soap and water before leaving the laboratory.

Procedure

Activity 1. Useful Mineral Properties

Test 1: Observations

1. Obtain the eight different mineral samples to be tested and identified. The mineral samples will initially be identified using numbers 1–8. (Note: By the end of Activity 1, the minerals will be identified by name.)
2. Place the Mineral Data Table on the tabletop and set each mineral sample next to its corresponding number on the data table. A very brief description of each mineral is provided in the table below so that the mineral may be matched with its number.

The Minerals

3. Use a magnifying glass to carefully observe each mineral. Record a detailed description of each sample in the Mineral Data Table. Be sure to include physical properties (e.g., color, shape, distinguishing features, unique characteristics). (Note: Descriptions should be clear enough that if the eight samples were moved or mixed up, they could be easily identified by number on the data table.)

Test 2: Light Interaction Test

The way that light bounces off or passes through a mineral tells something about how the atoms inside the mineral are arranged. The atoms in some minerals let light rays pass through, while some minerals have arrangements that make the light bounce right off. Each condition has been given a different name.

1. Look carefully at each mineral and decide if each is opaque, translucent, or transparent. Use the following definitions to classify each mineral:

   Opaque—No light can pass through the mineral. When the mineral is held up to a light, no light shows through.
   Translucent—Some light can pass through, but you can’t see through the mineral. A mineral is translucent if the edges look lighter when it is held up to a light.
   Transparent—Light rays can pass right through the mineral. Transparent minerals look like glass—you can see right through them.

2. Record all observations in the Mineral Data Table.

   Some transparent minerals also show a unique property called double refraction. Double refraction is caused when the light rays are bent—making everything looked at through the mineral appear double!

3. Test each transparent mineral for double refraction. To do this, lay each transparent mineral across the straight and wavy lines below or over some writing (see Figures 3 and 4). Look at the lines through the mineral. Slowly rotate the mineral and see if any of the lines appear double, causing “double vision” to occur.
   {13549_Procedure_Figure_3 and 4}
4. Record all observations in the Mineral Data Table.

Test 3: Streak Test

The “streak” of a mineral is the color of the mineral’s powder. The streak of a mineral can be different than the color of the mineral itself. Sometimes the color of the outside of a mineral is changed by contact with the air, rain or water and other minerals in the ground.

1. Obtain a white streak plate.
2. Take each mineral sample and rub it once or twice on the streak plate.
3. Record the color of the powder that rubs off each mineral in the Mineral Data Table.

Test 4: Mineral Hardness Test

Hardness describes how resistant a mineral is to being scratched. This is different than breaking or shattering a mineral. To determine hardness, either scratch the mineral or, use the mineral to scratch something else. A geologist named Friedrich Mohs developed a scale for rating the hardness of minerals. The higher the number, the harder the mineral, with 10 being the hardest. Each mineral will scratch those with a lower number, but will not scratch those with a higher number. Determine the hardness of each mineral by trying to scratch each one with your fingernail, the penny, the nail or the streak plate.

1. Obtain a steel nail. Determine the hardness of each mineral by first trying to scratch each with a steel nail (hardness = 5). This is easiest to do on a flat surface of a mineral.
2. Split the eight minerals into two groups—minerals that the steel nail can scratch (hardness less than 5) and minerals that the nail cannot scratch (hardness greater than 5). (Note: Minerals that the steel nail can’t scratch should be able to scratch the steel nail.)
3. For each mineral that was classified with a hardness of less than 5, try to scratch each with a copper penny (hardness = 3) and then with your fingernail (hardness = 2). Categorize each mineral using the same logic as in step 2.
4. For each mineral that was classified with a hardness of greater than 5, try to scratch each with a ceramic streak plate (hardness = 7). Categorize each mineral using the same logic as in step 2.
5. Estimate the hardness of each mineral based on the hardness of each comparison tool. Record the hardness of each mineral in the Mineral Data Table.

Test 5: Cleavage Test

Cleavage is a word used to describe how a mineral splits or breaks. Some minerals form perfectly flat surfaces when they break. This is called cleaving. Mineral 3 is an example of a mineral that has perfect cleavage. Thin sheets of the mineral can actually be peeled off, and the surface left behind is perfectly flat! Most minerals cannot be easily peeled apart like mineral 3. To test most minerals for cleavage they need to be hit or shattered.

Teacher Demonstration

The teacher will demonstrate how minerals are tested for cleavage by breaking mineral 5.

Safety Precaution: Testing for cleavage requires shattering the mineral with a hammer. Safety goggles or some type of protective eye covering should be worn while doing this test!

1. All of the minerals being tested have already been broken from larger pieces. Look at the broken surfaces on each mineral sample and describe the mineral’s cleavage. Use the following definitions to describe each mineral.
   Perfect Cleavage—The broken surface is perfectly flat. Light reflects off when tilted back and forth.
   Good Cleavage—Some of the broken surfaces appear perfectly flat. When the mineral is tilted back and forth in the light, there appears to be one position that reflects light very well.
   Poor/No Cleavage—The broken surfaces are irregular. Although the mineral might be shiny, none of the surfaces are perfectly flat.
2. Record all descriptions in the Mineral Data Table.

Test 6: Smell Test

Some minerals have very unique or distinctive smells. It is easiest to smell a mineral if a fresh sample of its powder is obtained.

1. Test the minerals in the following order: 8, 7, 6, 5, 4, 3, 2, 1. Rub each mineral back and forth a few times on the streak plate. Immediately smell the powder.
2. Record all observations in the Mineral Data Table.

Test 7: Ice Test

Some minerals behave very uniquely when they come in contact with ice. In this test, each mineral is placed on an ice cube to see what happens!

1. Put nine ice cubes onto a piece of paper towel. Put one piece of each mineral onto each ice cube. (Note: One ice cube will be empty to serve as a “control.”)
2. Watch the ice cubes for five minutes. Record all observations in the Mineral Data Table.

Test 8: Solubility Test

Solubility is a word used to describe how well things dissolve. In this test, the solubility of the minerals will be tested in two liquids, water and vinegar (acetic acid). The solubility test will be performed as a class experiment.

Class Experiment

1. Fill eight 100-mL beakers with about 50 mL of tap water.
2. Fill eight other 100-mL beakers with about 40 mL of vinegar, a weak acid.
3. Place one piece of each of the minerals in each beaker of water and in each beaker of acid. Label the beakers. Allow the minerals to sit in the liquids for one or two days or until no further observable changes are apparent.
   Use the following terms to describe each mineral:
   Soluble—The mineral dissolves easily in the solvent, either water or acid.
   Slightly soluble—The mineral appears to dissolve to some extent in the solvent.
   Insoluble—The mineral does not appear to dissolve at all in the solvent.
4. Record all observations in the Mineral Data Table.

Mineral Identification

5. Identify each mineral by name in Column 1 of the Observations and Evidence table. Use a table of known mineral properties (either from a textbook or provided by the instructor). Some recorded evidence may be conflicting—this is okay. Evaluate all the data against the known properties and make the best guess.
6. Answer the Post-Lab Questions for Activity 1.

Activity 2. Rocks and Stomach Acid

1. Obtain a small sample container, 10 mL of vinegar, and 2 pieces of pH paper. The vinegar solution represents stomach acid.
2. Using a graduated pipet, place 10 mL of vinegar into the sample container (stomach).
3. Dip a piece of pH paper in the vinegar solution. Record the pH of the vinegar solution in the Rock Data Table.
4. Obtain 7 or 8 pieces of limestone (calcium carbonate).
5. Place the limestone pieces (antacid) in the vinegar solution. Record any observations in the Rock Data Table.
6. Cover and shake the sample container for 3 minutes.
7. After the 3 minutes have elapsed, dip another piece of pH paper in the limestone/vinegar solution. Record the pH of the solution and all additional observations in the Rock Data Table.
8. Answer the Post-Lab Questions for Activity 2.
9. Consult your instructor for appropriate disposal procedures.

Student Worksheet PDF

13549_Student1.pdf