Mineral IdentificationMineral Identification

Minerals can be identified by a Minerals can be identified by a combinationcombination of their physical of their physical properties (characteristics).properties (characteristics).

COLORCOLORSome minerals come in more Some minerals come in more

than one color. Ex. Quartzthan one color. Ex. Quartz

Some different minerals have Some different minerals have similar colors. Ex. Fluorite and similar colors. Ex. Fluorite and Amethyst QuartzAmethyst Quartz

LUSTERLUSTER Definition: How a mineral reflects light.Definition: How a mineral reflects light. Luster can be divided into two categories:Luster can be divided into two categories: A. A. Metallic- Metallic- Shines like a metalShines like a metal

1. metallic shiny – ex. Graphite and 1. metallic shiny – ex. Graphite and GalenaGalena

Metallic LusterMetallic Luster

2. Metallic Dull- looks more like a rusty 2. Metallic Dull- looks more like a rusty nailnail

LUSTERLUSTER

B.B. NON-METALLIC- NON-METALLIC- doesn’t shine like a doesn’t shine like a metalmetal

1.1. GlassyGlassy luster ex. Quartz luster ex. Quartz

Non-metallic lusterNon-metallic luster

2. 2. PearlyPearly- shine like a pearl ex. Talc- shine like a pearl ex. Talc

Non-metallic lusterNon-metallic luster

3. 3. SilkySilky luster- shines like corn silk luster- shines like corn silk

ex. Gypsumex. Gypsum

Non-metallic LusterNon-metallic Luster

4. 4. Waxy Waxy luster- shines like candle waxluster- shines like candle wax

ex. Some Quartz and some Haliteex. Some Quartz and some Halite

Non-metallic LusterNon-metallic Luster

5. 5. EarthyEarthy Luster- “shines” like dirt Luster- “shines” like dirt

ex. Bauxiteex. Bauxite

Non-metallic lusterNon-metallic luster

6. 6. Resinous Resinous Luster- shines like sticky Luster- shines like sticky honey or amber ex. Sphaleritehoney or amber ex. Sphalerite

One kind of mineral can have two different One kind of mineral can have two different forms and so it may have two types of forms and so it may have two types of luster.luster.

ex. Hematite- it may be Specular Hematite ex. Hematite- it may be Specular Hematite which is metallic-shiny, or it can look which is metallic-shiny, or it can look metallic-dullmetallic-dull

Mini LabMini Lab

1. Get a tray -divide the minerals in to two 1. Get a tray -divide the minerals in to two groups: metallic and nonmetallicgroups: metallic and nonmetallic

2. Divide the metallic minerals in to two 2. Divide the metallic minerals in to two groups: shiny and dull metallicgroups: shiny and dull metallic

3. Group the nonmetallic minerals by 3. Group the nonmetallic minerals by glassy, pearly, silky, waxy, earthy, and glassy, pearly, silky, waxy, earthy, and resinous lusterresinous luster

STREAKSTREAK Streak-color of a mineral’s powder when Streak-color of a mineral’s powder when

scratched on an unglazed porcelain tile called a scratched on an unglazed porcelain tile called a streak plate streak plate

Not all minerals leave a streak!Not all minerals leave a streak!

HARDNESSHARDNESS

Hardness- a mineral’s resistance to being Hardness- a mineral’s resistance to being scratched scratched

Friedrich Mohs invented Friedrich Mohs invented Mohs Scale ofMohs Scale of HardnessHardness

Diamond- hardest mineral; Talc softest Diamond- hardest mineral; Talc softest mineralmineral

MOHS SCALE OF HARDNESSMOHS SCALE OF HARDNESS

1010 Diamond – the hardest mineralDiamond – the hardest mineral 99 CorundumCorundum 88 TopazTopaz 77 QuartzQuartz 66 Orthoclase (Feldspar)Orthoclase (Feldspar) 55 ApatiteApatite 44 FluoriteFluorite 33 CalciteCalcite 22 GypsumGypsum 11 Talc – represents the softest mineralTalc – represents the softest mineral

MNEMONIC DEVICEMNEMONIC DEVICE

To learn Mohs Scale of Hardness, To learn Mohs Scale of Hardness, memorize the following sentence:memorize the following sentence:

““To Get Candy From Aunt Fanny, Quit To Get Candy From Aunt Fanny, Quit Teasing Cousin Danny.”Teasing Cousin Danny.”

Did you notice that the first letter of Did you notice that the first letter of each word in the sentence corresponds each word in the sentence corresponds to the first letter of each word in Mohs to the first letter of each word in Mohs Scale? This is a mnemonic device Scale? This is a mnemonic device (memory aid)(memory aid)

MOHS SCALE OF HARDNESSMOHS SCALE OF HARDNESS

1.1. Talc (softest)Talc (softest) To To 2.2. Gypsum Gypsum Get Get 3.3. Calcite Calcite Candy Candy 4.4. Fluorite Fluorite From From 5.5. Apatite Apatite Aunt Aunt 6.6. Feldspar Feldspar Fanny Fanny 7.7. Quartz Quartz Quit Quit 8.8. Topaz Topaz Teasing Teasing 9.9. Corundum Corundum Cousin Cousin 10.10. Diamond (Hardest)Diamond (Hardest) Danny Danny

COMMON OBJECTS TO HELP COMMON OBJECTS TO HELP TEST MINERAL HARDNESSTEST MINERAL HARDNESS

The following objects can be used to help The following objects can be used to help determine the hardness of a mineral:determine the hardness of a mineral:

Fingernail –Hardness of 2.5Fingernail –Hardness of 2.5 Copper Penny- H: 3.1Copper Penny- H: 3.1 Iron Nail – H: 4.5Iron Nail – H: 4.5

Glass Plate – H: 5.5Glass Plate – H: 5.5 Steel File – H: 6.5Steel File – H: 6.5 Streak Plate – H: 7.0Streak Plate – H: 7.0

Mini LabMini Lab Divide the minerals into metallic and Divide the minerals into metallic and

nonmetallic luster and check with teachernonmetallic luster and check with teacher Check the streak of the metallic and Check the streak of the metallic and

nonmetallic minerals and tell your teacher nonmetallic minerals and tell your teacher what you found out (AHA!!)what you found out (AHA!!)

Take the nonmetallic minerals and line Take the nonmetallic minerals and line them up by hardness using tools and the them up by hardness using tools and the minerals themselves to help you!minerals themselves to help you!

Memorize Moh’s Scale for a quiz next Memorize Moh’s Scale for a quiz next weekweek

CLEAVAGECLEAVAGE Cleavage- the way a mineral may split Cleavage- the way a mineral may split

easily along flat surfaceseasily along flat surfaces

Planes of weaknessPlanes of weakness

Ex.) Halite has an atomic structure that Ex.) Halite has an atomic structure that forms cubic breakage forms cubic breakage

Geologists use hammers and Geologists use hammers and knives to determine how a mineral knives to determine how a mineral

breaksbreaks

Minerals may have very Minerals may have very distinctive cleavagedistinctive cleavage

Mica-one direction of perfect cleavage.Mica-one direction of perfect cleavage. Calcite (rhombic) and Galena (cubic)- Calcite (rhombic) and Galena (cubic)-

cleavages in 3 directions. cleavages in 3 directions.

Cleavage can be observed under Cleavage can be observed under a microscope in a thin sectiona microscope in a thin section

FRACTUREFRACTURE Fracture -the way a mineral breaks Fracture -the way a mineral breaks

unevenly, unevenly, not not with smooth, flat surfaceswith smooth, flat surfaces Examples:Examples: a. a. Conchoidal fractureConchoidal fracture -a curved, shell- -a curved, shell-

like pattern, like broken glass; ex. Quartzlike pattern, like broken glass; ex. Quartz

OTHER FRACTURE PATTERNS OTHER FRACTURE PATTERNS

b. b. Fibrous fractureFibrous fracture looks splintery. Ex. looks splintery. Ex. Gypsum and AsbestosGypsum and Asbestos

MORE FRACTURE PATTERNSMORE FRACTURE PATTERNS

c. c. Irregular or unevenIrregular or uneven fracture- shows no fracture- shows no definite pattern; ex. Hematite and definite pattern; ex. Hematite and MagnetiteMagnetite

CRYSTAL SHAPECRYSTAL SHAPE

Some minerals can be identified by their Some minerals can be identified by their crystal shape-crystal shape-

a. a. CUBICCUBIC – Ex. – Ex. Pyrite, Halite, GalenaPyrite, Halite, Galena

OTHER CRYSTAL SHAPESOTHER CRYSTAL SHAPES

b. b. HEXAGONALHEXAGONAL- six sided crystals- six sided crystals

Ex. Corundum and QuartzEx. Corundum and Quartz

MORE CRYSTAL SHAPESMORE CRYSTAL SHAPESc. c. RHOMBICRHOMBIC- shaped like a parallelogram; ex. - shaped like a parallelogram; ex.

CalciteCalcite

SPECIAL PROPERTIES OF SPECIAL PROPERTIES OF MINERALSMINERALS

Some minerals have very distinctive Some minerals have very distinctive properties that can be used to identify properties that can be used to identify them:them:

a. a. EffervescenceEffervescence (acid test) – when HCL (acid test) – when HCL (hydrochloric acid) is added to calcium (hydrochloric acid) is added to calcium carbonate (CaCOcarbonate (CaCO33), it causes bubbling as ), it causes bubbling as carbon dioxide (COcarbon dioxide (CO22) is released; ex.) ) is released; ex.) Calcite is a mineral that bubbles with acidCalcite is a mineral that bubbles with acid

EFFERVESCENCE-EFFERVESCENCE-Acid testAcid test

MORE SPECIAL PROPERTIESMORE SPECIAL PROPERTIES

b. Double Refraction-b. Double Refraction- an optical property an optical property of some varieties of calcite that gives a of some varieties of calcite that gives a double image effect.double image effect.

MORE SPECIAL PROPERTIESMORE SPECIAL PROPERTIES

c. c. Magnetism-Magnetism- minerals with this property minerals with this property are attracted to magnets; ex. Magnetiteare attracted to magnets; ex. Magnetite

SPECIAL PROPERTIES SPECIAL PROPERTIES CONTINUEDCONTINUED

d. d. Fluorescence-Fluorescence- property where the property where the mineral glows under ultra-violet light; ex. mineral glows under ultra-violet light; ex. Fluorite and some calcitesFluorite and some calcites

MORE SPECIAL PROPERTIESMORE SPECIAL PROPERTIES e. e. RadioactivityRadioactivity- minerals that contain - minerals that contain

radium or uranium can be detected by a radium or uranium can be detected by a Geiger counter. They give off radiation Geiger counter. They give off radiation (gamma rays).(gamma rays).

SPECIFIC GRAVITYSPECIFIC GRAVITY Specific Gravity Specific Gravity is the heaviness of a is the heaviness of a

mineral as compared to water. It’s similar mineral as compared to water. It’s similar to density. Pyrite has a s.g. (or density) of to density. Pyrite has a s.g. (or density) of 5.0. Remember water is 1.0.5.0. Remember water is 1.0.

MORE ABOUT SPECIFIC MORE ABOUT SPECIFIC GRAVITYGRAVITY

Used to compare two similar looking Used to compare two similar looking minerals- minerals- PyritePyrite (fools gold) looks like (fools gold) looks like Gold Gold but has a lower specific gravity numberbut has a lower specific gravity number

WHAT NOW?WHAT NOW?

It’s time to practice what you have learned It’s time to practice what you have learned about properties of minerals by identifying about properties of minerals by identifying 15 important minerals. 15 important minerals. Good luckGood luck! !

Don’t depend on your partner- there will be Don’t depend on your partner- there will be a challenging mineral lab test at the end of a challenging mineral lab test at the end of the unit.the unit.