BLM Leg 1 #11	Rock and Mineral Identification
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Rock and Mineral Identification: Adapted from Canada-Manitoba Partnership Association for the Western Economic Partnership Agreement. Rocks, Minerals and Mining. Adapted by permission of Manitoba Energy and Mines.

To identify rocks and minerals, prospectors may refer to books. Read the following descriptions to identify the rocks and minerals in your collection.

ROCKS 

Granite

Granite is a rock that forms when minerals crystallize together from a magma. The three most common minerals in granite are quartz, mica, and feldspar. To help you identify granite, here is a description of the three minerals: 
•	Quartz grains resemble clear or grey irregular pieces of glass. 
•	Mica is a mineral that flakes off in thin sheets. It can be black or white. 
•	Feldspar reflects light off its flat faces and can be either salmon pink or whitish.

With a magnifying glass about 10 X in power, examine your rocks and see if any rock fits the description of granite. Separate this rock from your collection. If you have made an error do not worry. It will become clear as you identify more rocks in your collection. 

Two common varieties of granite that are found in Manitoba:
•	Brownish red granite is found near Pinawa. After this granite is polished on site, it is sent to the United States and elsewhere to be used in buildings and monuments. 
•	Lighter granite is found near Whitemouth. This granite is quarried in rough blocks, and sold to build monuments such as headstones.

Gypsum Rock

The sample you have is a combination of gypsum crystals that form gypsum rock. Gypsum is usually white, and soft enough that it can be scratched with a coin. It sometimes has the appearance of sugar candy. Can you identify your specimen of gypsum?

Gypsum has a wide variety of uses. In Manitoba, it is used to produce Portland Cement or wallboard. Besides being used for cement, gypsum is used in toothpaste, Plaster of Paris, beads, filters for beer and wine, and to whiten paper, textiles, and bread. It is also used for carving figurines or statues. Large, clear crystals of gypsum called selenite are popular with mineral collectors.

Gypsum is mined in open pit quarries at Gypsumville and Amaranth in Manitoba. The gypsum found in this area was deposited by a large ancient lake that extended into North Dakota and Saskatchewan. When the seawater of this ancient lake evaporated, gypsum (calcium sulphate chemically combined with water) or anhydrite (calcium sulphate without water) was deposited.

BLM Leg 1 #11	Rock and Mineral Identification (Continued)
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Limestone

Limestone is found over large parts of Manitoba because ancient seas once covered part of our province. Limestone is quarried, crushed, and heated in kilns to make cement, which, combined with gravel, forms concrete. Since concrete is so widely used, people consider limestone the most important rock in civilization. You may also have seen limestone gravel or aggregate used to pave roads, so you should have no trouble identifying this rock.

Stonewall, Manitoba, is the main source of limestone for Winnipeg. If you live in Manitoba you probably know where to find limestone. Depending on how much erosion the limestone fragments have undergone, they may be rounded or angular. If the limestone is rounded and contains clay, it makes good gravel to pave country roads. Angular limestone can make excellent concrete.

Dolomite

Dolomite is limestone that contains magnesium. The dolomite in your collection is whitish, with grey lines running through it. Manitoba is famous for this type of dolomite deposit.

A farmer named Gunn found the first deposit of dolomite in 1895. It is reported that Gunn tried to sink a well and kept hitting very hard limestone. Later, this type of layer of limestone became known as the Gunn Formation. Similar deposits are found in the following locations in Manitoba: Stony Mountain, Garson, Tyndall, Grand Rapids, The Narrows, and Pelican Rapids. Garson and Tyndall have important dolomite deposits. Initially, in the early 1900s, when the quarries opened, Garson did not yet exist as a town, and therefore dolomite was shipped by train only from Tyndall. Soon, this beautiful building stone became known as Tyndall stone.

Tyndall stone has been used to beautify buildings all over North America. Some of the finest buildings in Canada, including the Manitoba Legislative Building and the Centennial Concert Hall in Winnipeg, are built with Tyndall stone. Tyndall stone is a popular building material because it resists weathering, has a variety of colours, is easy to cut, and contains fossils.

Copper Ore

Copper can occur in pure form as native copper nuggets. The yellow cholcopyrite in your collection is a copper sulphide. When exposed to oxygen, in air or water, cholcopyrite may tarnish to a blue or green colour. Humans have used copper in its pure form for 8000 years. There is evidence of early humans using pure copper for arrowheads.

BLM Leg 1 #11	Rock and Mineral Identification (Continued)
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In its purest form, however, copper is too soft to be used in many objects. To make it more useful, it is mixed with other metals. For instance, when mixed with tin, it becomes bronze, used in ship propellers. When copper is mixed with zinc, it forms brass.

Copper was discovered in the Flin Flon area of Manitoba in 1915. When this deposit was discovered, there was a book circulating among prospectors called Sunless City. In the book, the main character, Josiah Flintabbatey Flonatin reached an imaginary gold mine. Having just read the book, the prospectors named their new copper find Flin Flon. This copper ore has zinc, gold, and silver mixed with it. 

Copper has been used in a variety of tools, weapons, ornaments, and coins. Today, its properties of conducting heat and electricity make it useful in cooking pots and electrical wire.

Zinc Ore

Zinc is a metal with a silver bluish colour. In Manitoba, zinc commonly occurs with copper. The largest deposits discovered to date are located in the Flin Flon region. Zinc dissolves in hydrochloric acid and can be scratched by a steel needle. Zinc readily reacts with air to produce a corrosion-resistant skin of zinc oxide. This property makes it useful for protecting iron and steel products. The coating of other metals with zinc is called galvanizing. Zinc is also combined with copper to form the alloy brass. Canada is the largest producer of zinc, and one-quarter of the zinc used in the western world comes from Canada.

Nickel Ore

Nickel is a metal with a dull steel colour. Nickel ore was discovered where Thompson, Manitoba, is today. The mine at Thompson opened in 1957 and started producing nickel in 1961. Today, ore is mined using both open pit and underground mining methods. The deposit at Thompson is so rich that International Nickel (INCO), the company that owns the Thompson mine, built a smelter to process the nickel ore. Over the years, Thompson has grown to be Manitoba’s third largest city, due primarily to the flourishing mining industry.

Nickel was first identified in 1751 by A.F. Constedi, a Swedish scientist. Today, it is one of the world’s most important metals as it adds strength, hardness, and corrosive-resistant qualities to various metal alloys. For example, nickel is used in stainless steel alloys.

Potash

Potash is very soft and can be scratched by a piece of glass. Potash has a high concentration of potassium, which makes it a valuable source of fertilizer. A large potash deposit has been located between St. Lazare and Russell in western Manitoba.

BLM Leg 1 #11	Rock and Mineral Identification (Continued)
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Minerals

Garnet

Garnet is a reddish mineral that forms a 12-sided crystal, a shape referred to as dodecahedron. Garnets are found at many localities in the Precambrian Shield, including Snow Lake, Manitoba. Because garnet is especially hard, garnet chips are used to make abrasive papers (sandpaper). Garnet gemstones are the birthstones for people born in January.

Quartz

Quartz has a glassy appearance, which geologists call “lustre.” Quartz forms a crystal with six sides (hexagonal) and is usually colourless, grey, or white. This mineral is very hard and therefore can scratch most other minerals.

Quartz rock is not mined in Manitoba but is commonly found in this province. In rocks, such as granite, it occurs in grains that appear to be irregular pieces of glass. Sometimes impurities occur in quartz, which can change its colour. For instance, when quartz takes on the impurity manganese, quartz becomes purple and forms amethyst.

Quartz has many uses. It is used in the manufacturing of quartz watches. Quartz sand is used to make glass and in the production of silicon, which is then used to manufacture computer chips. Silica sand occurs on Black Island in Lake Winnipeg.

Feldspar

Feldspar is a common mineral found in granite, along with quartz and mica. It is not as hard as quartz. Feldspar comes in two colours, either white or salmon pink. Feldspar forms monoclinic crystals that have flat surfaces that reflect light. It is used in the production of powdered cream, porcelain, and glass. Perhaps you can find both types of feldspar in your collection or in rocks you find in your area.

Muscovite Mica

Although deposits of this mineral occur in Manitoba, muscovite mica is not mined commercially. Muscovite mica is clear and colourless and forms thinly cleaved crystals. Mica was once used to make reflectors in toasters and to make shatter-proof glass. Long ago, the windshield of the Model A-Ford car was made of mica.

BLM Leg 1 #11	Rock and Mineral Identification (Continued)
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Lepidolite

Lepidolite is a purple to lavender lithium-bearing mica. It is quite rare and may be found with other minerals that contain lithium.

In Manitoba, lepidolite is mined at Bernic Lake near Lac Du Bonnet. Here, it is mined with other uncommon minerals. Lepidolite is used in the production of heat resistant glass. Lithium is used in high temperature lubricants, rubber products, and textile dyes. Lithium carbonate is used as a drug to treat people who are manic-depressive (a mental illness).

Spodumene

Spodumene, a mineral that also contains lithium, generally forms white, yellowish, or greenish blocky crystals. It may occur in a form that can be used as a gemstone. Usually this rare mineral occurs in large grains or crystals with other minerals. Spodumene is mined at Bernic Lake, Manitoba, and used in the production of cooking containers. 

Sphalerite

Sphalerite is the main mineral of zinc ore. It is pale orange-yellow to red or black, depending on the amount of iron it contains. Sphalerite is mined in Manitoba at Flin Flon and Snow Lake.

Zinc is mainly used to coat other metals. This is called galvanizing. Galvanized metals are used in construction, automobiles, heating ducts, roofing, and siding. Zinc is also used in making rubber, paints, and drugs. When zinc is mixed with copper, the product is called brass, and is used in ornament, plumbing, and heating exchange units.

Pyrite

Pyrite is yellowish and has a metallic lustre. When you see pyrite, you will easily see why it has been called Fool’s Gold. Early prospectors used to put pyrite into water to see if it would rust. If the metallic mineral rusted, it was pyrite, but if it did not rust, the prospector knew the mineral was gold. Pyrite is used to make sulphuric acid and refrigerator fluid.