2 Mineral Characteristics Lab

7/23/2019 2 Mineral Characteristics Lab

http://slidepdf.com/reader/full/2-mineral-characteristics-lab 1/38

1

Mineral Descriptions

Chapter 2 Lab



2

Graphite

Graphite has layers, therefore it hascleaned age in one direction,sometimes the layers are you regular,in other words, the clean page is not intotally flat plane's. On the punctuation.When you look at graphite, the greasyLuster is very apparent and is opaque

and shiny gray. Graphite has ametallic luster, it is shiny dark gray,almost greasy looking in, is softer thanpaper. You can easily scratch it withyour fingernail. In fact, it is so soft thatit marks on paper, which is why it is the

major component of pencil at 10 pencilthat is not really lead it is graphite witha little bit of clay. Graphite can only beconfused with molybdenum night.However molybdenum I has more of abluish tinge to it and do them.

Generally is in little hexagonal crystalflakes.



3

Galena

The first thing you notice about Galenawhen you pick it up is the steel grayshiny metallic luster and how heavy itis. You notice the three cubiccleavage directions that is mostcharacteristic of Galena, and this is theway you tell it apart from any othermineral. It's fairly soft, you can notscratch it with your fingernail, andgalena will not scratch a penny.Galena in small pieces can beconfused with sphalerite. However,sphalerite is light brown to yellowishbrown color and has more cleavagedirections than the three cubicdirections than galena has. Galenacan be distinguished from graphite,because Galena is harder and heavier



4

Sphalerite

Sphalerite is a golden brown lightbrown or metallic brown. It is fairlyheavy, and it has more than fourdirections of cleavage. It has ayellow brown streak. Even when itis very metallic looking, it still hasa yellow brown streak. Sphalerite

is also fairly heavy, though not asheavy as Galena. Thecharacteristic luster of sphalerite isresinous. Resin is tree sap, or theresin is what violinists and otherstring players use on their bows.



5

Bornite

Bornite is also metallic in luster but its

doesn't have cleavage. in other words,it is irregular on all sides. There areno shiny flat planes or cleavageplanes. Although bornite looks, bronzeon fresh surfaces, on weatheredsurfaces it has a purplish iridescentsheen. That's why it is called peacock

ore. Even though the color looksbronze or black, the streak is gray,black. Bornite has a hardness aboutthe same as the hardness of a penny.So sometimes it scratches a pennyand sometimes the penny can scratchit. In particular, the tarnish rubs off

easily. Because bornite is metallic. Italso is relatively heavy, although notas heavy as sphalerite or Galena. Itcan easily be distinguished fromsphalerite or Galena, because it hasno cleavage.



6

Copper

Copper is metallic and has nocleavage. It is about as hard as apenny, but generally will notscratch a penny. On a freshsurface, copper has the samecolor as a new copper penny.When it is tarnished, it may be

black or dark brown or greenishcolored. Copper is malleable,which means that it is easy tobend. This is why you see thosemachines that will turn a pennyinto a charm with names or other

things on them. It's easy to rollthe penny into a flat shape.



7

Chalcopyrite

Chalcopyrite is also metallic with nocleavage. It looks like brass. Thecolor is a brassy yellow, and it canbe confused with gold. However,chalcopyrite is harder than gold.Even though, chalcopyrite is abrassy yellow color, it's streak is

greenish black. Whenchalcopyrite tarnishes, then it hasan iridescent sheen. Chalcopyritecan be confused with pyrite, whichis fools gold. However, pyrite willscratch glass, but chalcopyrite will

scratch a penny, but will notscratch glass.



8

Chromite

Chromite is also metallic,although it is not often shiny. Itis iron black in color, andsometimes is brownish black.It generally looks like cast iron.

Chromite does not have cleaveeach, and is generally irregularin shape. It generally hasconchoidal fracture, and isuneven, more brittle, and easy

usually granular. Sometimes itmay have very weakmagnetism.



9

Hematite

Hematite can be metallic in luster, or it can

be earthy, and nonmetallic. But themetallic variety is a silvery gray color,and the earthy variety is the rusty redbrown color. However, both types ofhematite have a reddish-brown streak.You may have to rub your hand acrossthe streak, to see the underlying color.

Hematite does not have cleavage, ascan easily be seen in the earthyvariety. However, the shiny grayvariety generally has sparkles ofsilvery gray plates. These are notcleavage planes, but they are crystalfaces. The hardness of hematite is

variable as the earthy variety is softerthan glass. But the Metallic silverygray variety may scratch glass.Hematite can be confused withmagnetite as it sometimes is magnetic.This usually occurs because somemagnetite is mixed in with the silvery

hematite. However the streak ofhematite will always be reddish brown.



10

Magnetite

Magnetite also has no cleavageand is metallic in luster. It isusually very black in color andwill leave a black streak.Magnetite will scratch glass.The most characteristic feature

of magnetite is that it will beattracted to a magnet.Magnetite and bornite lookalike, although bornite alwayshas a purple tarnish, where asmagnetite is always a black.

Also magnetite is harder thanglass.



11

PyritePyrite also has metallic luster and

looks like brass. The color ismore silvery brass or pale brass,rather than the deep yellow brass

of chalcopyrite. The streak ofpyrite is greenish black orbrownish black. Even though thecolor is a bright brass, pyrite willscratch glass. This is how youdistinguish it from gold, which is

soft enough to bite. Sometimepyrite looks like it has cleavagebecause it has cubic crystals orfive sided crystal faces. However,if you look along the sharp edgebetween two crystal faces, you will

see that the broken edge does notbreak in flat planes parallel to thecrystal faces. Instead, it breaks ina curved pattern that we callconchoidal fracture.



12

Talc

Talc is nonmetallic. It has layers,which means it has cleavage inone direction, which is in flatplanes. The layers of talc are notalways perfectly flat planes.Because talc is a metamorphicmineral, its layers are slightly

curved. Talc can be almost anycolor. It can be green, gray, white,pink, blue, or any other color. Thestreak is always white. The mostcharacteristic thing about talc isthat it is very soft. It is a much

softer than your fingernail. In fact,it has a very greasy feel to it. It isso soft that it is used as talcumpowder.



13

Gypsum

Gypsum is also nonmetallic andhas good cleavage. Thelayers in gypsum are very flatplanes in the variety selenite.The layers in gypsum arefibrous in the variety satin spar.

The variety alabaster is verymassive and does not appearto have cleavage. One of themost characteristic thingsabout gypsum is the softness.It is much softer than your

fingernail. Gypsum is usuallyclear or white, and the streak isalso white.



14

Muscovite

Muscovite is clear or white mica.It is clear or white or sparklysilvery or bronze, but does nothave metallic luster, becauseyou can see through it, in otherwords, it is transparent totranslucent. The mostcharacteristic thing aboutMuscovite is the very thin,clear, flexible sheets.

Sometimes you can scratchMuscovite with yourfingernails, and sometimes it isharder than your fingernails,and you can scratch a penny

with the Muscovite.



15

Halite

Halite is also nonmetallic in lusterand has good cleavage inthree directions, in a cubicshape. Halite is slightly harderthan your fingernail, but will notscratch a penny. The mostcharacteristic thing about haliteis its salty taste and its cubiccleavage. It is usuallycolorless to white. Halite is

common table salt and you canlook at table salt with yourhand lands or magnifying glassand see the cube shapes. Trycrushing some of the coarser

salt and see if they are stillcubic shapes.



16

BiotiteBiotite is black mica. It is

black to brown and isnonmetallic. Even though

it is dark colored, you can

see through the thin

sheets. The hardness isvariable, and sometimes

you can scratch it with

your fingernail and

sometimes it will scratcha penny. Thin sheets are

also flexible, and can

bend.



17

Calcite

Calcite is also nonmetallic in luster and

has good cleavage in three directions.However, these three directions arenot at right angles to each other. Theshape is more like a cube that hasbeen pushed over on one side. Thisshape is called rhombohedral. Calcitecan be any color. Clear to white is

most common, but calcite can be pinkor green or blue. Calcite is about thesame hardness as a penny, andsometimes will scratch a penny. Themost definitive characteristic of calcite,is the fact that it will fizz or effervescein dilute hydrochloric acid. The

reaction of hydrochloric acid withcalcite releases the gas carbondioxide. Carbon dioxide is the gas thatis released in the bubbles in soda pop.



18

BariteBarite is also nonmetallic and has a

good cleavage in two directionsand poor cleavage in the third

direction. Barite is about the samehardness as a penny, and willusually scratch the penny. Bariteis usually quite and sometimeshas a slightly pinkish or fleshcolored tinge to it. It can also be

clear or blue or yellow or almostany other color, but it does have awhite streak. The mostcharacteristic thing about barite isthat he is very heavy for anonmetallic mineral. In other

words, it is about twice as heavyas a similar sized piece of calcitewould be. Another characteristicthing about barite is that it isusually tabular. In other words, itis longer and wider than it is thick.Sometimes barite can form roses.



19

DolomiteDolomite is also nonmetallic and hasgood cleavage. It has a verysimilar composition to calcite andhas a similar cleavage. Dolomite

has rhombohedral cleavage, inother words, cleavage in threedirections like a pushed overcube. Dolomite will fizz inhydrochloric acid, only if youpowder the mineral first. If themineral has rhombohedralcleavage, and does not fizz inHCl, then use a knife or a nail toscratch a piece of the mineral tomake a powder, then put a drop ofhydrochloric acid on that powderto see if it fizzes. Dolomite can be

many colors from white to pink totan colored to gray, but the streakis generally white. Dolomite isabout the same hardness ascalcite and will most likely scratcha penny. Dolomite often forms

small, bladed crystals that arecurved.



20

FluoriteFluorite is also nonmetallic with good

cleavage. However, the cleavageis in four directions. So there are

more planes than a rhombohedralcleavage. Sometimes, thesecleavage planes will form anoctahedron in which there is apyramid on the top and a reversepyramid on the bottom. Fluoride

has a hardness of four, whichmeans that it will scratch a penny,but will not scratch glass. Fluoritecan be any color from purple towhite to clear to pink to green toblue to yellow to brown. Fluorite

commonly occurs in cubiccrystals. Although fluorite canlook like calcite or barite or otherminerals, it's hardness between apenny and glass is characteristic,as well as the good octahedroncleavage in four directions.



21

Sphalerite

Sphalerite can look nonmetallicwhen it has a resinous luster.It has cleavage in more thanfour directions, which is shownby the many flat planes ofcleavage. It has a hardness

between a penny and glass.Spell right can be yellowyellow brown to brown toblack, but its streak isgenerally reddish-brown toyellowish brown. The resinous

luster and many directions ofcleavage are characteristic ofsphalerite.



22

Hornblende (an amphibole)

Hornblende is also nonmetallicand has two directions ofcleavage that aren't not at rightangles. The two directions ofcleavage are at angles of 120°and 60°, not at 90°.Hornblende is usually black ordark green to brown. Eventhough this mineral is very darkcolored, it does not look like ametal, but looks more likeblack glass. Hornblende isharder than glass.



23

Orthoclase

Orthoclase is also nonmetallicand has two directions ofcleavage that are at rightangles. It is also harder thanglass and is about the samehardness as the streak plate,which is porcelain, which ismade from orthoclase.Orthoclase is generally white,pink or herb pinkish tan incolor. However, the varietyamazonite, is bright green.

Another characteristic oforthoclase is the mottlednature.



24

Plagioclase

Plagioclase is also nonmetallicand has two directions ofcleavage that are at rightangles. Plagioclase is also afeldspar and is harder thanglass and is about the samehardness as the streak plate.Plagioclase can be white, gray,blue-gray, gray, black, oriridescent blue. Someplagioclase has thecharacteristic of twinning,which results in striations on acleavage face. Thesestriations look like fine parallelgrooves, similar to corduroy orgrooves on a record.



25

Limonite

Limonite has anonmetallic luster withno cleavage. It is anearthy, yellow brown

to brown mineral thathas a yellow brownstreak. Limonite can

be scratched with afingernail.



26

Steatite

Steatite is the massivevariety of talc. It is softer

than your fingernail and

has a greasy luster and is

very slippery. The colorof steatite can be green,

gray, white, and other

colors, but the streak is

always white.



27

Bauxite

Bauxite is also nonmetallicwith no cleavage. It isrelatively soft and will notscratch a penny. It canbe white, gray, yellow,red, brown, and dull, butits streak is white. Thecharacteristic form ofbauxite is pisolitic, which

means there are small,round grains of differentcolor is in an earthy,claylike, matrix.



28

Sulfur

Sulfur is alsononmetallic and hasno cleavage. It isvery soft and can bescratched by yourfingernail. It has adistinctive brightyellow color, and hasa yellow to white

streak. It smells likesulfur. It is brittle,and it crackles withthe heat of your hand.



29

Kaolinite

Kaolinite is nonmetallic,with no cleavage. It is

very soft and is

usually chalky clay. It

is white, dull, an

earthy, and is plastic

when wet. It will stick

to your tongue.



30

Hematite

Hematite is earthy, looksnonmetallic, and has nocleavage. It has a rustyto reddish brown color inits nonmetallic variety.

The characteristic streakis reddish brown. Thehardness is variable andcan be scratched with afingernail in its earth, the

massive state or canscratch glass.



31

MalachiteMalachite is nonmetallic and has

no flat planes and no cleavageplanes. Malachite is a bright

green and can be a light greenor dark green. Malachite willscratch a penny but will notscratch glass. The luster ofmalachite can be either earthyor glassy. The form can bebotryoidal or stalactitic inshape. Botryoidal meansrounded concentric layers andbuilt one on top of the other.Malachite is copper carbonate,

which has a similar chemistryas calcite and dolomite.Therefore, when you scratchmalachite and make a powder,it will fizz in dilute hydrochloricacid.



32

Azurite

Azurite is also nonmetallicand has no flat planes orcleavage planes. Azuriteis a bright blue and canbe either light blue or

dark blue. Azurite willscratch a penny but willnot scratch glass. Theluster of azurite can beeither earthy or glassy.

The form can also bebotryoidal in shape. Azurite is also coppercarbonate, and powderedazurite will also is in dilutehydrochloric acid.



33

Chrysocolla

Chrysocolla is also nonmetallic

and has no flat planes werecleavage planes. Chrysocollais a bright blue-green, similarin color to turquoise. Theluster is earthy to glassy, and it

is always massive and notcrystalline. It has acharacteristic conchoidalfracture. Chrysocolla has ahardness between two to four,

which means you can notscratch it with your fingernail,and it may or may not scratcha penny.



34

Olivine

Olivine is also nonmetallic and

has no cleavage. Olivine is atypical olive green to darkgreen color. It ischaracteristically in small,green, glassy grains. It will

scratch glass, a making a deepgroove. However, the grainsare brittle, and will break off,making it seem like they arenot as hard as glass. Looking

at the grains with a magnifyingglass, the conchoidal fracturecan be seen. Olivine is themineral name for the gemstoneperidot.



35

Quartz

Quartz is also nonmetallic and has no

cleavage. Quartz has a glassy togreasy luster. It will scratch glassleaving a sharp groove. Quartzcan be almost any color. Thepurple variety is called amethyst.The pink variety is called Rose

Quartz. The smoky yellow tobrown and black variety is calledsmoky quartz. The light yellowvariety is called citrine. Theconchoidal fracture ischaracteristic of quartz. Quartzcommonly occurs in hexagonalcrystals with a point on one end.Looking at the sharp edges of thefaces of these crystals indicates aconchoidal fracture where are theedges are broken or dinged.



36

ChertChert, Flint, and Jasper are

forms of granular Quartz.These minerals are

nonmetallic and have nocleavage, although theydo have conchoidalfracture, which made

them valuable to India inthis for making arrowheads and spear points.These minerals can beany color, although they

are usually colorless,white, red, gray, andother colors. They arevery hard and will scratchglass.



37

GarnetGarnet is also nonmetallic and

has no cleavage. It is veryhard and will scratch glass,

making it a deep groove in theglass plate. Garnet has a veryglassy to resinous guru andluster. Garnet frequentlyoccurs in crystals in the shapeof dodecahedrons, or 12-sided

crystals. These have diamondshaped faces. These crystalfaces may be confusing, andthat they might look likecleavage faces. However,when you look at the placewhere two crystal faces joinwith a magnifying glass orhand lens, you will see that thebroken edges have conchoidalfracture.



38

Topaz

Topaz is also nonmetallicand has only basalcleavage, which meansthat the base of thecrystal may have a flat

plane. Topaz is very hardand will scratch glasseasily. Topaz commonlyoccurs in four-sided,prismatic crystals, which

have a pyramid shape onthe end. Topaz can bemany colors, eithercolorless or white, or tanor brown or other colors.

2 Mineral Characteristics Lab

Documents

Transcript of 2 Mineral Characteristics Lab