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Home , Lustre (mineralogy)

Lab 2:

Reading Understanding Earth, Ch. 3, and Appendix 4

Objectives • To learn how are classified • To learn the common properties of groups • To identify common minerals found in the Earth’s crust

Introduction

The crust of the Earth is made up of a variety of different rocks. Each type of is formed from an assemblage of minerals. Minerals are the basic "building blocks" of rocks, and the recognition of common minerals and rocks is an essential part of the study of geology.

A mineral is defined as a chemical element or compound that is a naturally-occurring crystalline and is formed as a result of inorganic processes.

The terms "rock" and "mineral" are often erroneously used interchangeably. It is important, therefore, to emphasize the key differences between these materials. A mineral is a substance formed by nucleation and growth in an “orderly, three dimensional array.” It is relatively continuous and homogeneous, with a set chemical composition or range of compositions. A rock is an aggregate of minerals with possible wide variations in chemical compositions and structures. A mineral can be represented by a chemical formula, while a rock cannot.

Figure 2.1 The difference between a mineral and a rock. Left: The mineral . Right: The rock eclogite, made up of garnet and clinopyroxene.

Although there are over 3000 minerals that have been discovered, fewer than 30 make up the bulk of the earth's crust. These are called the rock-forming minerals, and are the ones you are most likely to encounter in the rocks around you.

Classification of Minerals

Groups of related minerals are called classes. Minerals are classified on the basis of the anion (negatively-charged atom or atom group) in their crystal structures. In nature about one-third of the known mineral types are silicates, and they make up about 95% of all the minerals in the Earth's crust. The remaining 5% include all the other groups of minerals.

Table 2.1 The Major Chemical Classes of Minerals Mineral Class Anion Examples

4- -oxygen tetrahedral (SiO4 ) in , pyroxene, , , Silicates a number of different linkages (pg. clays, , amphibole, 56-57, mineral book) , garnet, chlorite

2- Carbonates carbonate (CO3 ) , , Native elements no anions; minerals consist of one sulphur, , , native element only copper, gold , , , Sulphides sulphur (S2-) , oxygen (O2-) and/or , , , Oxides/hydroxides hydroxyl (OH-) , bauxite Halides fluorine (F-) or chlorine (Cl-) , ,

2- Sulphates sulphate (SO4 ) , , barite

3- Phosphates phosphate (PO4 )

Many of the characteristics of minerals within a class have similar physical properties, because of similarities in their crystal structure.

Physical Properties of Minerals

Each mineral has characteristic physical properties that are easily determined and are useful in identification. A mineral's diagnostic properties are those few that are most distinct and useful for accurate identification. For example a diagnostic property of calcite is the vigorous effervescence you see when hydrochloric acid (HCl) is applied.

The most important properties are hardness, habit, , and colour. There are also certain unique properties that apply to certain minerals or mineral classes, such as , magnetism, acid reaction, taste, and odour.

1. Lustre

The lustre of a mineral is the amount and quality of light reflected from the mineral surface. The most common kind of luster is vitreous lustre. Vitreous lustre, as the name implies, means the lustre is glassy. It stands to reason that vitreous lustre is the most common lustre, because silicates are the most abundant mineral class, and the distinguishing chemical characteristic of silicates is the presence of SiO2. The amorphous state of SiO2 on its own is glass of the kind used in windows.

Metallic lustre is much more rare, as it is found primarily in metal-bearing sulfides and oxides.

A few minerals have a metallic look to them, but not quite as much as those with a true metallic lustre. These minerals can be described as submetallic.

Table 2.2 Classification of Lustre

LUSTRE APPEARANCE MINERAL EXAMPLES (proper terminology) (improper proper terminology) • transmits light as well as reflects it (like Vitreous • quartz, fluorite, olivine, garnet clear or coloured glass)

• has a soft, lustrous shine to it, like • , talc (in laminae), Pearly mother-of- gypsum (on cleavage faces)

• , limonite (vitreous to Earthy • dull, granular, like soil earthy) • talc (when massive), graphite, Greasy • appears to be coated by an oily substance sulphur (resinous to greasy)

Adamantine • brilliant lustre • diamond

• bright grey, highly reflective, (almost • galena, Metallic like a mirror) • magnetite • dull grey/black, but "sparkly"

• brassy/gold, reflective • pyrite, chalcopyrite

Submetallic • borderline glassy/metallic • graphite, some hematite

2. Hardness

The hardness of a mineral is one of the most useful properties we can use to identify a mineral specimen. Hardness is a measure of the specimen’s resistance to abrasion or scratching. It is usually determined by the nature of the chemical bonds within the mineral. For example, both graphite and diamond are composed of carbon atoms; however, the carbon atoms bond differently within each specimen. Diamond has strong chemical bonds between the carbon atoms and is the hardest mineral known; graphite has weakly bonded carbon atoms and can be scratched with a human fingernail.

Hardness can be tested and observed by scratching the surface of a mineral sample with another reference mineral of known hardness. These reference minerals are arranged in a standard hardness scale known as “Moh’s Scale of Hardness” (see Table 1.3). The standards are numbered from 1 to 10 in order of increasing hardness. Each mineral will scratch the one below it in the scale, but not the one above it. For example, fluorite will scratch calcite, but not apatite. Also, because a significant amount of geological work is done in the field, relationships of hardness to common objects such as fingernails, knives, glass plates, and streak plates, is often used.

Table 2.3 Moh’s Hardness Scale and common items that may be used for comparison

Moh’s Number Mineral Common Item 1 talc 2 gypsum fingernail (2-2.5) 3 calcite copper penny (3.5) 4 fluorite 5 apatite glass plate (5-5.5) 6 steel knife (5-6) 7 quartz streak plate (6.5-7) 8 9 corundum 10 diamond

TESTING HARDNESS

1. Try to find the cleanest, "freshest" looking part of the sample specimen and find a smooth surface on which to test. Press a sharp corner of the reference material (e.g., fingernail, penny, quartz) against the specimen, and make a firm upward or downward movement of a couple of millimeters.

2. Check if you have made a scratch by wiping away any powder. A fine scratch may be evident in the specimen. Use your hand lens to have a closer look.

3. If the sample specimen is scratched by the reference, then the reference is harder and has a higher number on Moh’s Scale. However, if the reference is scratched by the sample, then the sample has a higher number on Moh’s Scale. By bracketing the hardness of a mineral versus the references, you can provide a small range in which the hardness of the mineral fits.

For example, if a mineral scratches a penny (with a hardness rating of 3.5) but will not scratch a glass plate (with a hardness of 5.5), then we say that the hardness of the mineral is 3.5-5.5.

3. Cleavage and

Many mineral specimens are found as broken samples rather than well-defined . The shape and pattern of the broken mineral is useful for identifying mineral samples.

Cleavage is the tendency of a mineral to break along well-defined planes which represent planes of weakness in the crystal lattice. For example, mica can be endlessly split along its single cleavage plane, producing sheet after sheet of flat, transparent flakes. Minerals that have cleavage can have up to six distinct sets of cleavage planes. Some of these cleavage planes are illustrated in Figure 2.2 below.

Figure 2.2 Types of Cleavage

One direction (also called basal cleavage)

cleavage plane crystal faces

Two directions at 90 o Two directions not at 90 o cleavage planes

fractu re s urfaces

Three directions at right angles Three directons not at right angles (cubic cleavage) (rhombic cleavage)

Four directions. The four cleavage planes are the surfaces represented by the cut off corners of a cube. 3 4

1 2

2

3 4 Table 2.4 below summarizes cleavages for a number of common minerals.

Table 2.4 Cleavage planes of some common minerals Type of Cleavage Example No cleavage à Fracture quartz, garnet, hematite, pyrite, olivine One plane (basal cleavage) graphite, , , talc Two planes at 90° pyroxene, feldspars Two planes not at 90° Three planes at 90° (cubic) galena, halite Three planes not at 90° (rhombic) calcite, dolomite Four planes fluorite More than four planes sphalerite

Fracture is how a mineral breaks along a non-cleavage plane. Many minerals will break with no observable pattern and are said to have uneven fracture. Figure 2.3 below compares how light reflects off of a cleavage surface an uneven fracture surface. Some minerals break with no observable pattern, but have a more distinct fracture such as a conchoidal fracture, where the fracture surface is curved and smooth, similar to a clamshell. Conchoidal fractures may be observed on the surfaces on broken glass and . Most of the glassy minerals (quartz, garnet, olivine, etc.) have conchoidal fracture.

Light rays

A cleavage surface is a planar surface that An uneven fracture surface is a non-planar reflects light from extensive, parallel flat surface that reflects light from many different surfaces. angles.

Figure 2.3 Reflection of light from cleavage and fracture surfaces

HINTS FOR DETERMINING CLEAVAGE

4. Look for flat, shiny surfaces on your mineral specimens, and note the number of planes of those surfaces. Mica, for example, has one plane of cleavage, while galena has three.

5. Determine the approximate angle between cleavage planes. For example, feldspar's two cleavage planes intersect at 90°, whereas calcite's three planes intersect at 60° and 120°.

6. If you are having difficulty determining cleavage, check the mineral tables to see what type of cleavage your mineral should have.

4. Specific Gravity

The specific gravity of a mineral is a measure of its density. More specifically, it is defined as the density of the mineral divided by the density of water. For example, the density of galena is 7.5 g/cm3; thus, its specific gravity is calculated as 7.5 g/cm3 divided by the density of water, which is 1 g/cm3. In other words, galena has a specific gravity of 7.5. Note that specific gravity is a unitless number.

If a mineral has the same density as water, it has a specific gravity of 1.0. We find that the metallic minerals of the sulphide group generally have a much higher specific gravity than the non-metallic minerals. Of the minerals in the sulphide tray, galena has the highest specific gravity. Among non- metallic minerals barite, with a specific gravity of 4.5, is the densest.

5. Colour

The colour of a mineral results from the absorption of certain wavelengths of light by the mineral, while other wavelengths are reflected. Colour is of limited use in identifying mineral samples, because many minerals occur in a variety of colours. For example, quartz varies from clear to white, pink, yellow, gold, green, blue, violet, and even dark grey or black. Clearly, quartz would be much more easily identified by another property, for example its hardness! However, in rock samples, colour is often a good indicator of mineralogy. For instance, granite is made up of quartz, k-spar and . In most samples, quartz will be grey, k-spar will be pink, and plagioclase will be white. Nevertheless, variations do occur, and colour should always be used in unison with other properties.

Different minerals may display the same colour. For example, both quartz and fluorite have purple varieties. Another example is pyroxene and some amphiboles, which may display a dark greenish-black colour. In this case, since their hardness’ are similar, use cleavage to tell them apart.

The exceptions to this rule are the metallic minerals, most of which have a distinct and specific colour. Pyrite ("fool's gold"), pyrrhotite, and chalcopyrite are all metallic, gold-coloured minerals, but they have very clear differences in shading. Most of the native elements (copper, sulphur, graphite, silver, etc.) are also easily distinguishable by colour, at least on an unweathered surface.

6. Habit

The habit of a mineral is the shape in which a mineral tends to grow. This is as opposed to cleavage, which is the way a mineral tends to break. A mineral’s habit is the result of which surfaces on the crystal lattice grow the fastest. Equant crystals grew with each surface growing at approximately the same rate, while crystals had one surface grow very much faster than all the others.

Figure 2.4 7. Streak

The term streak refers to the colour of the mineral when a portion of it is crushed along a porcelain streak plate, and is more diagnostic than colour in the case of the sulfide class. These minerals will always have a constant streak, regardless of their colour. For instance:

Pyrite ...... greenish-black streak Magnetite ...... black streak Hematite ...... reddish-brown streak Limonite ...... yellow-brown streak Graphite...... silver-grey streak Galena ...... silver-grey streak

Sometimes the streak is the same colour as the mineral, but this is not always the case. Many minerals (especially silicates) have a white streak. Some minerals have no streak at all, because their hardness is greater than that of the streak plate. Most non-metallic minerals, such as calcite, talc, gypsum, and fluorite, give a white or very pale streak.

8. Reaction with Acid

Carbonate minerals can be distinguished from other minerals by their reaction with acid. For example, calcite samples will fizz audibly when exposed to a drop of hydrochloric acid (HCl). Dolomite, while also a carbonate, may or may not fizz when exposed to HCl, because of the presence of Mg and Fe. The rate of reaction may be increased by adding the acid to a freshly scratched surface of the mineral.

Although HCl present in the lab is a very weak acid, be careful not to get HCl in open cuts, in your eyes, on your clothes, or in your mouth. Do NOT use HCl on any mineral that has a metallic lustre. A foul odor would ensue. Use a paper towel to wipe off the acid when you are done testing.

9. Other Unique Properties

Magnetism- A few metallic minerals are attracted by a magnet. Magnetite is strongly magnetic; hematite, pyrrhotite, and chalcopyrite are weakly magnetic.

Odour- A few minerals have a distinctive smell. Kaolinite (a clay mineral) is the constituent of earth or soils which imparts the distinctive “earthy” odour when moistened slightly. Sphalerite will give off a characteristic sulfurous (“rotten egg”) smell when dilute HCl is placed on it. The smell of a mineral sample can sometimes be enhanced by smelling the streak instead of the mineral.

Feel- Some minerals have a greasy or soapy feel to them due to either their basal cleavage (e.g. graphite, talc) or to dissolution of the mineral by moisture on your hand (e.g. halite). Other minerals may have a silky, woody, or smooth texture.

Taste- A few minerals will readily dissolve at room temperature and give a distinctive taste. For example, halite is salty. However, some minerals may have toxic effects; it is not safe to taste minerals with a metallic lustre.

Striations- Some minerals will have striations, which are very small, parallel lines on a mineral surface (e.g., /////) that can be seen with the aid of a hand lens. Striations can sometimes be seen on the cleavage planes of plagioclase feldspar or on the crystal surface of pyrite.

The following three-part table (Table 2.6) lists ten metallic minerals along with their physical properties. The entries are grouped into parts by hardness.

TABLE 2.5 Minerals with metallic lustre 1. HARDNESS LESS THAN 2.5 (CAN BE SCRATCHED WITH FINGERNAIL) CLEAVAGE MINERAL STREAK and/or H S.G. OTHER (COMPOSITION) FRACTURE Black Perfect cleavage on 1 2 Bright silver-grey. Greasy feel. Graphite one plane Leaves a mark on paper. C One plane 1.5 4.65 Bluish grey. Greasy feel. Often Molybdenite Grey occurs in platy masses. MoS2 3 planes at right 2.5 7.5 Lead gray colour; commonly in Galena angles cubic crystals. PbS 2. HARDNESS 2.5 - 5.5 (HARDER THAN A FINGERNAIL, SOFTER THAN GLASS)

STREAK CLEAVAGE &/or H S.G. OTHER MINERAL FRACTURE (COMPOSITION ) * 3.5-4 4 Dark greenish-gold, often Chalcopyrite tarnished. Similar to pyrite, but (CuFeS2) not in cubic crystals. * 3 5 Blue-black when fresh; often with Black purplish, iridescent tarnish. (Cu5FeS4) * 4 4.6 Bronze metallic colour. Magnetic Pyrrhotite to varying degrees. (Fe1-xS) Yellow 6 good (6 poor); not 3.5 4 Submetallic or resinous; brown, Sphalerite easy to see in every yellow, black varieties; strong (ZnS) specimen sulphur smell when acid added. 3. HARDNESS GREATER THAN 5.5 (HARDER THAN A KNIFE) CLEAVAGE MINERAL STREAK and/or H S.G. OTHER (COMPOSITION FRACTURE ) No cleavage; 5 5 Brassy yellow; commonly in Pyrite conchoidal fracture cubes with striated faces, also FeS2 found in granular masses. Black * 6 5.2 Iron black; strongly magnetic. Magnetite Fe3O4 Red- * 5.5- 5.3 Only the rare black variety has a Hematite brown 6.5 metallic lustre. Fe2O3 *This property is rarely seen or measurable. S.G. = specific gravity The following four-part table (Table 2.6) lists 22 non-metallic minerals along with their physical properties. The entries are grouped into parts by hardness. The table extends over two pages.

TABLE 2.6 Minerals with non-metallic lustre 1. HARDNESS LESS THAN 2.5 (SOFTER THAN A FINGERNAIL) CLEAVAGE MINERAL STREAK and/or H S.G. OTHER (COMPOSITION FRACTURE ) Perfect cleavage on 2-2.5 2.8 A colourless mica; can be peeled Muscovite one plane into transparent sheets. (KAl2(AlSi3O10) (OH)2) White Perfect cleavage on 2-2.5 2.6- Various shades of green; mica-like Chlorite one plane 3.3 mineral. (Complex Fe-Mg sheet silicate) Perfect cleavage on 1 2.7- Greasy feel; green, grey, and Talc or one plane 2.8 white varieties common. (Mg3Si4O10(OH)2) Cleavage: 1 perfect, 2 2.32 Clear, colourless; fibrous or Gypsum two good. massive white and grey varieties. (CaSO4 . 2 H2O) Colour- Perfect cleavage on 2-2.5 2.6 Dull, earthy, powdery; distinctive Kaolinite less one plane * earthy odour. (Al2Si2O5(OH)10) Green/ Perfect cleavage on 2.5-3 3 A dark-coloured mica; flakes into Biotite brown one plane thin sheets. (K(Fe,Mg)3 (AlSi3O10)(OH)2) 2. HARDNESS 2.5 - 5.5 (HARDER THAN A FINGERNAIL, SOFTER THAN A KNIFE) CLEAVAGE MINERAL STREAK and/or H S.G. OTHER (COMPOSITION) FRACTURE Red- 5.5- 5.3 Reddish-brown; often found in Hematite brown 6.5 earthy masses. (Fe2O3) * 1-5 3.6-4 Earthy, powdery masses, and as Limonite * coatings on other minerals. (FeO(OH) . n H2O) 6 planes * 3.5 4 Resinous to submetallic lustre; Sphalerite colours vary from light to dark (ZnS) 3 planes at right 2.5 2.2 Colourless to white; cubic Halite angles crystals. Salty taste. (NaCl) White 3 planes, not at right 3 2.7 Usually white. Rhombic crystals. Calcite angles Reacts with HCl. (CaCO3) or 3 planes at right 3-3.5 4.5 Colourless or white. Unusually Barite angles high specific gravity for (BaSO4) nonmetallic mineral. Colour- 4 planes 4 3.2 Glassy; may be clear, purple, light Fluorite less green, blue, or yellow. (CaF) *This property is rarely seen or measurable. S.G. = specific gravity

TABLE 2.6 Minerals with non-metallic lustre (cont’d) 3. HARDNESS 5.5 - 6.5 (HARDER THAN A KNIFE, SOFTER THAN A STREAK PLATE) STREAK CLEAVAGE and/or H S.G. OTHER MINERAL FRACTURE (COMPOSITION) 2 planes at right 6 2.5- Colour variable, pearly-glassy Feldspars White angles 2.6 lustre; Plagioclase has twins on (KAlSi3O8) some cleavage surfaces. (Ca(Al2Si2O8)) (NaAlSi3O8) Colour- 2 planes (56o and 5-6 3-3.4 A type of amphibole; black, Hornblende less 124o) elongate crystals (Chain silicate with Ca, Na, Fe, Mg, Al, OH) two planes at 56o and 5-6 3-3.3 A dark green amphibole; elongate to 124o crystals. (Chain silicate with Ca, Fe, Mg, OH) 2 planes at 87o and 5-6 3.2- Single chain structure; dark green (Pyroxene) Pale 93o 3.3 to black prismatic crystals. (Chain silicate with Ca, Na, Mg, Fe, Al) 1 perfect, 1 poor 6-7 3.3 Apple green to black colour. Green Not at 90o Elongate crystals, some striated. (Complex silicate with Ca, Al, Fe, OH) 4. HARDNESS GREATER THAN 6.5 (HARDER THAN A STREAK PLATE) CLEAVAGE MINERAL STREAK and/or H S.G. OTHER (COMPOSITION) FRACTURE no cleavage; 7 3.5- Equidimensional 12-sided Garnet family conchoidal fracture 4.3 crystals; vari-coloured - red, (Complex Ca, Fe, Mineral green, brown, black Mg, Al, Cr, Mn silicate) scratches no cleavage; 7 2.65 Crystal shape (when visible) - Quartz conchoidal fracture elongate, 6-sided prisms. More (SiO2) streak often shapeless glassy grains. Wide range of colour - yellow, plate. pink, clear, black, purple, green. Does not Two planes with 7 & 3.6 Bladed crystals, blue or white. leave different hardness 4 (Al2SiO5) powder. 4 planes * 10 3.5 Brilliant lustre; equidimensional Diamond 8-sided crystals. Colourless, blue, (C) pink, yellow. * This property is rarely seen or measurable. S.G. = specific gravity

The following table (Table 2.7) lists several minerals along with their economic uses. The table extends over two pages.

TABLE 2.7 Economic significance of some common minerals

MINERAL USES Amphibole (silicate) A few varieties are used as gems, but generally only of interest to collectors and scientists. Apatite (phosphate) Fertilizer (source of phosphorus); sometimes good glassy crystals used as . & (Cu Valuable ornamental stones; deep blue (azurite) and green (malachite) sometimes carbonates) used as gemstones, though they are fragile and scratch easily. Barite (BaSO4) High specific gravity makes it a useful additive for drilling for oil. Also used as ballast in ships. Bauxite (Al oxide) An aggregate of hydrous aluminum oxides. Major ore of aluminum, used to produce synthetic corundum. Biotite (Fe, Mg silicate) Of interests to petrologists and collectors, and EASC 101 students. Calcite (CaCO3) Fertilizer, soil conditioner; fillers in rubber & paint; limestone, marble used in buildings and sculpture. Celestite (SrSO4) Main ore for strontium, used in fireworks and flares (crimson flame); much sought by collectors. Chalcopyrite (CuFeS2) The major ore of copper; yields by-products of gold and silver. Chlorite (Fe, Mg Generally only of interest to scientists and collectors; useful metamorphic index aluminosilicate) mineral. Corundum (Al2O3) Abrasive; gem varieties are and . Diamond (C) Abrasive; gem. Dolomite (CaMg(CO3)2 Structural & ornamental stone, metallurgy (metallic magnesium), chemical industry (magnesium salts) Epidote Some varieties used as gems, but generally only of interest to scientists and collectors. Feldspar (alumino- Major use in manufacture of porcelain, glass, and ceramics; minor use as silicates of K, Na, Ca) gemstones (amazonstone, , and sunstone). Fluorite (CaF2) Production of hydrofluoric acid; clear crystals are used as lenses and spectrographic prisms. Galena (PbS) Chief ore of lead; silver is a common by-product. Garnet (silicate) Gem variety is January birthstone; abrasive in sandpaper; metamorphic index mineral. Graphite (C) Lubricant for machinery; pencil "lead". Gypsum (CaSO4 . 2H2O) Wallboard, plaster of Paris, drywall, sheetrock; some ornamental use in form called alabaster. Halite (NaCl) Used as table and road salt; a source of sodium and chlorine chemicals. Old mines used as storage sites. cont’d… TABLE 2.7 Economic Significance of Some Common Minerals (cont’d)

Hematite (Fe2O3) Major ores of iron; minor use as a pigment (cave paintings were often done with Limonite (Fe2O3 . n H2O) hematite). Magnetite (Fe3O4) Kaolinite The principle ingredient of potting clay; the purest clays produce the finest (complex aluminosilicate) porcelain and china. Kyanite (Al2SiO5) High-temperature porcelain; electrical insulators; important metamorphic index mineral. Muscovite Used in sheets as an electrical insulating material; ground up for use in wallpaper KAl2(AlSi3)O10(OH)2 and paint; computer chip substrate. Olivine Gem variety, , is August birthstone; used as a source of silicon for silicon ((Fe,Mg)2SiO4) chips in computers; also used as components in high temperature furnaces. Pyrite (FeS2) Ore of sulphur used to make sulphuric acid; mined also for iron or associated gold or copper. Pyroxene (silicate) Generally only of interest to scientists and collectors Pyrrhotite (Fe sulfide) Nickel-bearing deposits are main source of nickel, cobalt and platinum. Otherwise of no particular use. Quartz (SiO2) In the form of pure sand, for making glass; minor (, tiger's eye, , and ). Serpentine (silicate) variety used in fireproof materials and insulation. Siderite (FeCO3) Important iron mineral, free of sulphur and phosphorus and often rich in manganese. (Al2SiO5) Good index for temperature and pressure of metamorphic rocks; some varieties used in jewellery. Sphalerite (ZnS) The principle ore of zinc, as a component of brass and other alloys, and for galvanizing iron. Talc (Mg(OH) silicate) Talcum powder; soapstone for carving. Topaz (Al silicate) Gem Used to make high-pressure gauges, making use of its electrical properties; also (complex borosilicate) widely sold as semi-precious stones. Valuable ornamental stone. (Cu, Al phosphate) (ZrSiO4) Important ore for zirconium and thorium; some varieties are used as gemstone

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Name:______Date:______

Lab 2:

Exercise 1

Complete the Mineral Identification Worksheets on the following four pages using the resources listed below: • Powerpoint slides of the minerals located on google drive • The background information given in your lab manual • Lecture notes and text book (optional)

You must be able to distinguish the minerals from each other. Each mineral has one or more characteristic (diagnostic property) that enable you or anyone to identify each mineral.

Kit# Mineral Group Colour Hard-ness Lustre Streak Habit Cleavage/ Most Diagnostic fracture Characteristic

1 olivine silicate

2 pyroxene silicate

3 amphibole silicate

4 silicate

5 silicate

6 biotite silicate

7 quartz silicate Kit# Mineral Group Colour Hard-ness Lustre Streak Habit Cleavage/ Most Diagnostic fracture Characteristic

8 muscovite silicate

9 kaolinite silicate

10 talc silicate

11 gypsum sulphide

12 halite halide

13 calcite carbonate

14 dolomite carbonate Kit# Mineral Group Colour Hard-ness Lustre Streak Habit Cleavage/ Most Diagnostic fracture Characteristic

15 garnet silicate

16 kyanite silicate

17 chlorite silicate

18 silicate

19 graphite native element

20 copper native element

21 limonite oxide 2 Lab Kit# Mineral Group Colour Hard-ness Lustre Streak Habit Cleavage/ Most Diagnostic fracture Characteristic -

Assignment Assignment

22 hematitie oxide Grade: 23 magnetite oxide

Thispage is 24 galena sulphide left left intentionally empty.

25 pyrite sulphide

26 chalcopyrite sulphide

27 sphalerite sulphide