Rockology 101

Welcome to class! This is a place for students of all ages to learn about Rogers Group operations and products or just have a little fun!

Rockology 101: Learning
Bet You Didn't Know
How Aggregates Are Made
How Aggregates Are Transported
How Aggregates Impact Your Life
Why Quarries Are Good Neighbors
The Mining Process
The Open Road
Sand, It's Not Just For Beaches
Farmers Like a Twist of Aglime
Modern Life and The Rock
Properties of Rocks
Rockology 101: Fun Facts
Rockology 101: Activities

Modern Life and The Rock

Society places a high value on rock and mineral resources. Mining plays an integral role in producing modern life creature comforts, industrial production and economic success. People use mined, mineral resources each day, in almost everything we do. Because they are so much a basic part of our lives, we don't think of them very often.

Rogers Group would like to tell you a little about how rocks and minerals are used by you everyday and you probably never even knew it!



Calcite looks glassy. Calcite has smooth surfaces but will not stand up on all of them. Calcite can scratch a fingernail. Steel can scratch calcite. Calcite powder fizzes in vinegar. Clear calcite makes things look double. It is very closely related to Limestone, Lime, Chalk and Calcium Carbonate. Calcite is a common mineral. It often forms beautiful, pointed crystals. If calcite is not pure, it can be found in almost any color. The clearest calcite is called Iceland spar because it is common in Iceland. Stalactites and stalagmites in caves are made of calcite. Calcite is a main rock-forming mineral of sedimentary rocks. It is also found in metamorphic rocks. Calcite forms when the chemical called calcium carbonate settles out of solution. Calcite is used to make cement and lime for mortar in buildings. If you want to know if you have found calcite, scratch the surface of the rock. Do not wipe off the white substance which will appear. Place a small drop of vinegar on the scratch. It should bubble and fizz.

Calcium carbonate is a white powder or colorless crystalline compound, CaCO3, found mainly in limestone, marble, and chalk in the form of the mineral calcite; used in making lime, paints, plastics. It can be found in the production of Fertilizers, water treatment, food preservatives and animal feeds.


Limestone is light colored (white, gray, or tan). Limestone may be fine grained or made up of shells and shell pieces. Limestone powder fizzes in vinegar. Limestone is a common sedimentary rock. One type of limestone contains fossils. Limestone occurs in layers, or beds. The beds may be up to 30 miles thick! Limestone may be dissolved and redeposited in such places as rock fractures, caves, hot springs, and geysers. Various limestones originate in different ways, but all form in water. The most common limestone forms when lime (a compound of calcium and oxygen) undergoes a chemical process. It settles out of the water and builds up in layers that harden into limestone. Another type of limestone is formed by organisms. Corals, snails, clams, and one-celled organisms use calcite to make shells. When the organisms dies, the shells settle to the bottom. Thick layers of shells build up and harden into limestone. The fossil remains of organisms can often be seen in this type of limestone. Limestone is made up of the mineral calcite. 400 million years ago, the mid-continent of the United States was covered in a broad shallow sea. Much of today's modern day limestone deposits were formed from this sea.

Limestone is used in extensively in buildings, both inside and out. It is an important part of mortar and cements. Limestone can be used as an environmental cleaning agent in many air and water pollution abatement systems.

Cement is a powdered substance made of burned lime, clay, shale or gypsum mixed with water and sand to make mortar, or with water, sand and gravel to make concrete. Small pieces of pumice are mixed with cement and plaster to give these construction materials a lighter weight. Pumice is usually gray or white. Pumice is made up of silky glass fibers and many air holes. Most pumice will float on water. Pumice is volcanic glass. Thin glass walls separate the many air holes. Because of the air holes, pumice can float for many weeks before it becomes waterlogged and sinks. Pieces of pumice drift ashore almost every seacoast. Pumice forms when lava turns solid while gases are still bubbling from it. Pumice has a spongy and frothy texture.

Concrete is a hard, compact building material formed when a mixture of cement, sand, gravel and water dries. Perlite is used in concrete and plaster and as a soil for potting plants. Perlite is formed from heated obsidian rock. When obsidian that contains water is heated, it expands and pops just as popcorn does and forms perlite.

Crushed limestone is used for building and repairing roads, building construction, concrete, cement, metallurgical fluxing.

Dolomite is used in building stone, road aggregate and agricultural lime. It is limestone which contains magnesium carbonate in an amount equal to the calcium carbonate content of the stone.

Powdered limestone may be used to improve poor soil. Lime is obtained by the action of heat on limestone, shells, and other material containing calcium carbonate, used in mortar and cement, hydrated it neutralizes acid soil.

Chalk is a type of lime or limestone, essentially calcium, carbonate, calcite. Chalks is a limestone made up of shells from microscopic marine organisms. Natural chalk is white. Chalk is so soft that a fingernail can scratch it. Chalk powder fizzes in vinegar. The White Cliffs of Dover, England, contain large deposits of chalk.

Phosphate Ore, once separated from limestone and silica sand by milling, is made into fertilizers, industrial chemical compounds, and additives to food and toothpaste.

Marble is a hard crystalline or granular metamorphic limestone in varied colors and patterns, capable of taking a high polish; it is used in building stone and memorials. Most marble is white or light colored. Most marble is coarse grained. Marble can be scratched by steel. Vinegar makes powdered marble fizz. The best known marbles are the pure white marbles from Greece. Ancient Greece used marbles for statues and buildings, such as the Parthenon. Some marbles contain colored minerals. Marble forms from limestone. Great heat and pressure melt the calcite in the limestone. The calcite regrows into larger crystals. The hardened rock is marble. Marble is quite soft and is easy to cut, carve and polish. Marbles are made into statues, monuments, grave markers, and into elaborate designs for fireplace mantles.

Wollastonite is most commonly found in metamorphosed limestones. This mineral has a unique particle shape (acicular or fibrous) and has a white color when pure. It is used in ceramics, as a filler in paint and as a filler in plastics. 


Sphalerite Sphalerite is the material which produces zinc. Spalerite sometimes resembles the rock, Galena, which is used to produce lead. Its name comes from a Greek word meaning "tricky", because ancient Greek metalworkers often mistook it for galena and were annoyed when they couldn't get lead from it. The yellowish-brown ore is usually found within white and gray dolomitic limestone host rocks. Zinc has a wide variety of uses. Zinc is refined and used throughout the world largely to protect steel against rust. More than 5.2 million metric tons of this mineral are consumed annually. Zinc-coated steel, commonly called galvanized steel, helps to make steel last longer with very little maintenance. Nearly 40 pounds of zinc is in a typical automobile, found primarily on steel body panels and chassis parts. And zinc oxide, which is needed for curing rubber, is in every tire. Zinc oxide is used to soothe baby's diaper rash and your skin when you have sunburn, poison ivy, and blisters.

Zinc, heated to a liquid, is injected into die-casting machines and shaped to produce intricate parts. Zinc die castings are used in a wide array of precision parts for automobiles, airplanes, and appliances. Zinc is used for refrigerator handles, dishwasher buttons, and pull-knobs on washing machines. Brass, an alloy of zinc and copper, has been used for over 3,000 years. Brass, is fashioned into everything from door knobs to trumpets and beds. Zinc air batteries power hearing aids and rechargeable battery packs for lap-top computers. Zinc is also used in some pharmaceutical products as well as in some paints, chemicals, and rubber materials.

Zinc occurs naturally in the body and is an indispensable nutrient for humans, animals, and plants. Because it takes zinc to produce protein, the "building blocks" of life, zinc is essential for growth. Zinc is most available to the body from meat. A zinc-deficient diet can lead to slowed growth, dry skin conditions, mental lethargy, loss of appetite and eating disorders, impaired vision, and increased susceptibility to infection.


Granite is usually light colored, from nearly white to shades of gray and pink. Granite is coarse grained. The grains are large enough to see with the naked eye. The quartz in granite can scratch steel. Granite is the most common coarse-grained igneous rock. It is made up of quartz, feldspar, and grains of a dark mineral like potassium, mica, hornblende. Granite is hard and wears slowly. It is an igneous rock. Granite is frequently used in building stone and memorials. The Vietnam Veterans War Memorial in Washington, D.C. is made of polished black granite.


Plaster of Paris is made from a rock material called "gypsum". It’s a special material that doctors once used to make casts when people broke their arms and legs. The strangest thing happens to plaster of paris when it begins drying. Do you know what that is? It gets hotter when it begins to dry. This is called an "exothermic" reaction. Gypsum is considered to be a hydrated sulfate of calcium, occurring naturally in sedimentary rock; used in Plaster of Paris (wallboard) and chalk.

Gypsum is an evaporite and a product of precipitation from saturated brines or ancient playa lakes and restricted marine basins. This means that gypsum forms when seawater evaporates under arid conditions. The principle use of gypsum is in the production of wallboard. It is also a primary component of stucco and plasters, and in the manufacture of cement. Very high grade gypsum also finds food grade and pharmaceutical applications.

Gypsum can form sulfur through a chemical reaction. Natural sulfur is usually light yellow in color. Sulfur crystals are almost transparent. Sulfur crystals may be transparent yellow. Sulfur can appear to glisten or look greasy. Sulfur can be scratched with a fingernail. It has an identifiable, pungent odor. People sometimes called sulfur "brimstone" because, generally, sulfur can be found around the mouth of volcanoes or from the around the edges of hot springs. Many major sulfur deposits are in sedimentary rocks and can typically be found within quarries. In Central and South America, sulfur has been quarried from the craters of extinct volcanoes. Sulfur melts and burns at low temperatures.The warmth of a hand will cause sulfur crystals to expand at the surface and crack; you can even hear the crystals crackling. Specimens should be kept out of sunlight and handled as little as possible.

Sulfur is a mainstay of the chemical industry. It is used to make gunpowder, found on match tips and to make sulfuric acid, the acid in car batteries. Sulfur is used to make rubber, synthetic fibers, plastics, pigments, explosives, fertilizers, dyes, soil conditioners, insecticides, and in making paper. How can you tell if your rock contains sulfur? Tear some paper into tiny pieces like confetti and then rub the sulfur with a scrap of wool. Touch the rubbed sulfur to the paper. The sulfur becomes charged with static electricity and will attract such things as little bits of paper.

Pyrite consists of iron and sulfur and occurs in all classes of rock. Pyrite is often called "fool's gold" because it looks like gold. When pyrite is melted, the iron and sulfur in it separates. The sulfur is used to make sulfuric acid, the kind of acid in car batteries. Iron is produced as a by-product. Iron is used to make electric appliances, automobiles, buildings, office equipment, beverage and food cans and other containers, tools, and machinery.


Quartz Quartz crystals look glassy. A quartz crystal is six sided. It has a pointed tip and lines that run across each side. Quartz is very hard. Steel cannot scratch it. Quartz is found in every class of rock. Sand forms when quartz wears away from these rocks and is broken into tiny pieces. Most light-colored sand beaches are made up of tiny pieces of quartz. Some gems are quartz that is colored by other minerals. Purple quartz is called amethyst. Gray or black quartz is called smoky quartz. Quartz with uneven bands of color is called agate. Quartz crystals form as silica solutions cool in igneous, sedimentary, or metamorphic rocks. Colored quartz is often cut and polished to make jewelry. Quartz crystals cut in a certain way produce a small amount of electricity. This effect makes quartz crystals useful in radios, clocks, and watches. Quartz crystals can be melted and formed into lens and prisms. They are also used in heat lamps and sun lamps. Sand, or tiny quartz pieces, is used in making glass, porcelain, paints, abrasives, scouring soups, and ceramic ware. Use a hand lens to identify if you have a piece of quartz, look for the small lines that run across the sides of the crystal. These lines are on all quartz crystals.

Sand is a type of quartz. Sand grains are used in concrete, glass and industrial production. Sand on the beaches of Florida's Panhandle region sparkles white because it is nearly pure quartz. Silica is a mineral found in quartz and sand used in insulation, light bulbs, and TV's.
Sandstones are usually light colored (white, gray, or yellow) but sometimes dark red. Sandstones are grainy, gritty, and feel rough. Sandstones are made mostly from quartz and can scratch steel. Sandstone breaks around the rounded quartz pieces rather than through them. This is why sandstone is not as sparkly as glass. Some sandstones contain iron oxide, or rust. The rust makes these sandstones dark brownish red. Such sandstone was used to build New York City's famous "brownstone" apartments. Dinosaur footprints are found in sandstone quarries in Connecticut. Sandstone forms from old sand dunes or when quartz sand grains settle out of water. A cement material, such as calcite, dissolves in water and seeps down through the sand. It glues the grains together to form sandstone. Sandstone is a sedimentary rock composed largely of sand grains, mostly quartz worn down by wind, water and ice, held together by silica, or lime; used in building stone, abrasives, concrete and mortar mixes, bedding materials, and playground sand. 
Sandstone main use is in construction. It is easy to shape and does not wear easily. Sandstone is also important because of the spaces, or pores, between the grains. Deep in the earth, sandstone stores petroleum. Closer to the surface, sandstone stores groundwater. Sandstone is used for glass grinding, metal polishing, and sandblasting. It is also used to filter sand to remove bacteria and sediment from water supplies.

Quartzite forms from sandstone. Great heat and pressure melt the sandstone quartz grains together very tightly to form quartzite. Quartzite is usually light colored (white, gray, or yellow) but sometimes is dark red. Quartzite is made up of fine, shiny grains. the quartz in quartzite can scratch steel. Quartzites are among the hardest and most resistant of all rocks. They are made up mostly of quartz particles. Quartzite breaks right through the quartz grains. These broken grains make quartzite look sparkly. 

Quartzite is used for decorations as slabs or as broken pieces. Powdered quartzite is used to make some sandpapers, scouring compounds, and metal polishes. It is also used for roofing granules, road and sidewalk surfacing, in concrete, and as a substitute for sand and grave in other construction.


Shales are usually gray but vary from black to dull red. Shales are very fine grained. Shales are usually thin bedded with fairly uniform texture. Shales split into flat, shell-like fragments with curved edges. Shales can be scratched by steel. Shale is a sedimentary rock; fine grained, thinly bedded rock, largely formed by hardened clay, mud, and silt; splits into thin layers; it is used in cement and bricks. It is also used in concrete block, structural concrete, and highway surfacing.

Shales are soft and easily eroded rocks. They can be split with little effort. Some shales contain many fossils. Shales are mainly clay sediments that were deposited in the quiet environment of lake and ocean bottoms and then hardened into rock. Shales are used in the manufacture of cement, bricks, pottery and other ceramic products. Some shales are oil reservoirs. Billions of tons of oil shale are a potential source of petroleum for future use. The Chattanooga Shale in Tennessee contains as much as 15 gallons of oil per ton of shale and about .006 percent uranium, but at present neither is economical to extract.


Slate is commonly black or gray but may be almost any color. Slate is very fine grained. Slate breaks into flat plates with thin layers. Slate can be scratched by steel. Wet slate has an odor. Slate forms when shale, a sedimentary rock made of clay, is subjected to heat and pressure. Slate cleaves naturally into smooth-surfaced layers; it is primarily used as building stone and in blackboards.

Slate is very durable. It lasts for thousands of years without changing or deteriorating. Most of the slate mined in the United States comes from the area of the Appalachian Mountains. Slate was formerly used for blackboards. Slate is widely used for roofing, for flagstones to pave patios, and to face buildings. Pulverized to rock flour, it is used as a filler in paints, linoleum, and other products.


Galena Galena crystals are usually cubes. Galena is heavy. Galena has a bright, silvery-gray, metallic shine. Galena is a soft mineral. Steel can scratch it. Galena is composed of a compound of lead and sulfur. Galena is a main source of lead. Galena is found in veins, pockets, and replacement deposits in rocks made of a chemical called carbonate.

Galena, has been known for centuries, and lead, smelted easily from it, has been used since ancient times. The ancient Romans were the first to use lead and to make pipes to take water to and from their great cities. Lead from the mineral galena is used in car batteries and other types of batteries. Lead is also used in hospitals and labs to shield people from radiation. A lead compound is used in gasolines to prevent engine "knock". Other uses include red lead for coating construction steel, lead foil for toothpaste tubes, solder for cans and containers, and soundproofing for rooms and machinery.


Talc is usually apple-green, white or gray. Talc has a pearly shine. Talc feels greasy and slippery feel. Talc is so soft it can be scratched with a fingernail. Talc is fine grained. Another name for talc is soapstone. Talc forms when magnesium-rich rocks are changed, especially by heated water. The most familiar product made from talc is talcum powder. Talc does not conduct heat or electricity well and is resistant to acids. It is used for laboratory table tops and chemical and heat resistant sinks and vats. It is also widely used as a lubricant, a source of magnesium in refractory ceramics, and as insulation in electrical equipment.

In the United States, most of our talc is mined in Montana, Texas, New York, and Vermont. Large deposits of soapstone can be found in the metamorphic rocks of the Appalachian Mountains. Eskimos carved lamps and pots from soapstone. The Chinese often used talc for carving figurines. Tailors use small pieces of talc to mark cloth.


Coal is black or dark brown in color. Coal is lightweight. Coal may have a glassy shine. Coal can burn. Coal is the most widespread and abundant energy resource in the United States. Coal-bearing rocks occur in 37 or our 50 states. Sometimes, well preserved plant parts can still be seen. Coal is made of the element carbon and is usually classified as a sedimentary rock because it occurs in layers, or beds. Coal is the product of decomposition, compression, densification, and concentration of carbon from dense prehistoric swamps and bogs. Peat, is considered to be the first stage in the formation of coal. Peat turns into lignite (brown coal), which turns into bituminous (soft) coal, and eventually to anthracite (hard) coal.

Steadily growing energy requirements have focused attention on the use of coal as an energy source. Electric utilities use nearly 88 percent of the coal produced in the United States. Other large consumers of coal products are chemical and glass manufacturers, paper mills, and the steel and iron industries. The by-products of coal serve as the basis for many items used daily by Americans such as plastics, road-building materials, perfume, linoleum, synthetic rubber, charcoal briquettes, billiard balls, rubber cement and roofing shingles.


Borax comes from the rock called Kernite. Kernite is used in the production of boric acid and borax. Boric acid is used in the production of textile fiberglass (cars, boats, circuit boards, roofing shingles), ceramics (glazes), chemicals (corrosion inhibitors, insecticides, pharmaceuticals), and specialty glass (heat resistant glass, laboratory glass). Sodium borate, a white, anhydrous, crystalline salt with an alkaline taste; it is used as a flux in manufacturing of glass, soap, enamel and artificial gems. Several borate ores, including borax, colemanite and ulexite, can be found at the U.S. Borax mine near Boron, California’s largest mine. The mine supplies nearly half the world’s demand for refined borates.


An earthy material composed of silicates, used for brick, tile, porcelain, sewer pipes, and cement. Clays can be used for ceramics, rubber, paint and drilling mud. It is formed by the weathering of rock.

Kaolin is also known as China clay. Relatively pure deposits of kaolin are used for coating and filling paper, as a component of ceramics, and as a filler in paint, plastics, and rubber. Kaolin is Geogia's most valuable single mineral products.


Feldspar Feldspar is usually white or pink. It normally has a pearly shine and a greasy luster. Feldspar breaks into flat pieces. Feldspars are the most common group of minerals. A feldspar called othoclase breaks into flat, rectangular pieces. Plagioclase feldspar breaks into flat pieces that usually have curved edges. Plagioclase has small lines that run across the flat surface. Feldspars are important rock-forming minerals and are found in many kinds of igneous and metamorphic rocks. Feldspars can form in a wide range of temperatures and pressures. They are made up of aluminum compound and several other metals. Feldspar ultimately decomposes into clay minerals. Feldspars are used to make ceramics and ceramic glazes. The feldspar called moonstone is used as gemstone; it is a birthstone for June.

It can be considered a crystalline minerals made up of aluminum silicates with sodium, potassium, or calcium, usually glassy; it is used as flux in glass and ceramic manufacture, also used in abrasives, fillers in paint and plastics and in insulation.

Don't use color as a way of identifying feldspar. Tilt the feldspar back and forth in the light and look for a pearly shine. Lay it on the table. Does it lie flat? Feldspar breaks into pieces that usually have flat top and bottom surfaces.


Graphite is a soft, smooth, slippery-feeling substance found mostly in large lumps or flattish, six sided flakes in rocks. It splits easily into thin sheets and can also easily be crushed into powder. Graphite is one of the two mineral forms of carbon, and although it is soft and easily broken, the other form is the hardest substance known, diamonds.

When you write with a "lead" pencil, you're not really writing with lead at all. The dark marks are made of by the mineral graphite. People first began using sticks of graphite as writing tools in England in the 1500's. Today, powdered graphite is mixed with clay and water to form a paste that's squeezed out into long strings by machines. The strings are cut to pencil sized lengths and baked in ovens until hard. Each length is then fitted into two pieces of wood.

Graphite can take alot of heat without melting so it is used to make electrodes through which electricity is sent into things. It is slick and slippery without being gummy like grease so graphite powder is used to lubricate locks and clocks.


A white, tasteless powder, used in insulation and firebrick; used also in a mild laxative and antacid.


Muscovite Mica has a pearly shine. Mica splits into thin, transparent sheets. Micas are common rock-forming minerals. They are found in most granites. Light colored mica (muscovite) is the most common type. Black mica is called biotite. Mica that explodes like popcorn when heated is called vermiculite. Micas form in igneous and metamorphic rocks. Thin transparent sheets of mica (muscovite called isinglass) are used as windows in iron stoves. Micas are used as insulators in electronic equipment. Vermiculite is used for house insulation and as a type of soil for growing plants. Mica can be found in many beauty supplies and make-ups. Powdered mica mixed with water forms a white, greasy material that shines. It is used in paints and in the printing of shiny designs on wallpaper. Mica belongs to a family of colored or transparent minerals that separates into very thin leaves; it is frequently used in such things as electronics, electrical, insulators, filler and extender in plasterboard, cement, paint and drilling mud. Don't use color as a way of identifying mica. Peel off one thin sheet with your fingernail. The sheet will look like cellophane tape.


A hard, fine-grained white ceramic consisting of clay, quartz, and feldspar, used for sinks, bathtubs, toilets.


Heavy material such as water, sand or iron which has no function in machine except the increasing of weight. Crushed stone is used as ballast by railroad companies; it is laid in railroad track beds. Mixed with soil, it helps control erosion.

Other Industry Terms

Having qualities of pitch, tar or asphalt in their natural states; soft coal that produces much smoke and ash.

A type of excavating equipment which casts a rope-hung bucket a distance and collects material by pulling the bucket toward itself on the ground with a second rope.

A large, barge-like machine used in underwater excavation.

A substance used to promote fusion of metals or minerals.

A chemical element that lacks most of the typical metallic properties and is able to form chemical compounds with hydrogen.

The soil or rock that covers a deposit.

Any finely divided solid which has settled out, as from washeries.

A place where crushed stone is freed from impurities or dust by washing.