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Mineral Identification

 

Although nearly 2,500 minerals are known to occur within Earth’s crust, most are rare with only about 100 occurring in abundance. Of those 100 minerals, fifteen make up the common rock-forming minerals and only some of the remaining minerals have any economic value.

Use the app below to identify your minerals.

Step 1

Is your mineral metallic or nonmetallic?

Metallic Non-Metallic

Step 2

Determine the hardness of your mineral. Using a glass plate, see if the mineral scratches it. Be careful, make sure the glass is on a table, do not hold in your hand. Firmly grasp your mineral and draw it over the glass. If the mineral powders, then use your fingernail to feel if the glass is scratched.

Does your mineral scratch glass?

Yes No

Step 5

Use chart below to determine your mineral:

Mineral	Description
Hematite specular variety Fe2O3	Steel-gray to black to brown in color micaceous H: 5-6.5 G: 3.3-3.4 reddish-brown streak
Pyrite FeS2	Pale brass-yellow in color often occurs in cubes H: 6-6.5 G: 5 green-black to brown-black streak
Magnetite Fe3O4	Strongly magnetic black in color commonly occurs in masses or single, octahedral crystals H: 6 G: 5.2 black streak

H=hardness // F=fracture // L=luster // S=streak // G=specific gravity

Step 2

Determine whether your mineral is light-colored or dark-colored.

Is your mineral light-colored or dark-colored?

Dark Light

Step 5

Use chart below to determine your mineral:

Mineral	Description
Galena lead ore PbS	Silvery in color heavy H: 2.5 G: 7.6 perfect cubic cleavage lead gray streak
Chalcopyrite CuFeS2	Brass-yellow in color tarnishes to purple H: 3.5-4 G: 4.5 green-black streak
Sphalerite zinc ore ZnS	Brown, black, or yellow in color 6 directions of cleavage H: 3.5-3.5 G: 4 yellow, brown or white streak that has a rotten egg smell

H=hardness // F=fracture // L=luster // S=streak // G=specific gravity

Step 3

Determine the hardness of your mineral. Using a glass plate, see if the mineral scratches it. Be careful, make sure the glass is on a table, do not hold in your hand. Firmly grasp your mineral and draw it over the glass. If the mineral powders, then use your fingernail to feel if the glass is scratched.

Does your mineral scratch glass?

Yes No

Step 3

Determine the hardness of your mineral. Using a glass plate, see if the mineral scratches it. Be careful, make sure the glass is on a table, do not hold in your hand. Firmly grasp your mineral and draw it over the glass. If the mineral powders, then use your fingernail to feel if the glass is scratched.

Does your mineral scratch glass?

Yes No

Step 4

Determine whether your sample has cleavage. Does your mineral have cleavage?

Yes No

Step 5

Use chart below to determine your mineral:

Mineral	Description
Augite Ca, Mg, Fe, Al silicate	Dark green to black in color Cleavages at nearly right angles Short, prismatic 8-sided crystals H: 5-6 G: 3.3
Hornblende Na, Ca, Mg, Fe, Al silicate	Dark green to black in color 2 cleavages at 60o H: 5-6 G: 3.3 long, prismatic 6-sided crystals

H=hardness // F=fracture // L=luster // S=streak // G=specific gravity

Step 5

Use chart below to determine your mineral:

Mineral	Description
Garnet Ca, Mg, Fe, Al silicate	Silvery in color heavy H: 2.5 G: 7.6 perfect cubic cleavage lead gray streak
Olivine (Fe, Mg)2SiO4	Olive-green in color 2 cleavages at 60o H: 6.5-7 G: 3.3-4.4 Translucent to transparent Commonly occurs in granular aggregates with a sugary texture Conchoidal fracture

H=hardness // F=fracture // L=luster // S=streak // G=specific gravity

Step 4

Determine whether your sample has cleavage. Does your mineral have cleavage?

Yes No

Step 5

Use chart below to determine your mineral:

Mineral	Description
Sphalerite Zinc ore ZnS	Brown, black, or yellow in color 6 cleavage directions Yellow, sulfurous smell to streak H: 3.5-4 G: 3.9-4.1 L: resinous S: yellow
Biotite K(Mg, Fe)3AlSi3O10	Black-brown in color 1 perfect cleavage H: 2.5-3 G: 2.7-3.1 L: Vitreous Thin plates are elastic S: white
Chlorite Mg, Fe, Al silicate	Green in color 1 perfect cleavage H: 2-2.5 G: 2.6-2.9 Nonelastic scaly masses S: white to pale green

H=hardness // F=fracture // L=luster // S=streak // G=specific gravity

Step 5

Use chart below to determine your mineral:

Mineral	Description
Hematite earthy variety iron ore Fe2O3	Reddish-brown in color Cleavage is not obvious H: 5 G: 5.3 S: reddish brown L: usually earthy May show rounded forms
Kaolinite clay Al4Si4O10(OH)8	White to red in color Earthy masses H: 1 Earthy odor and luster Behaves plastically when wet Resembles chalk
Limonite iron ore Fe2O 3H2O	Yellow to brown in color Earthy masses H: Earthy masses S: yellow-brown G: 3.3-3.4

H=hardness // F=fracture // L=luster // S=streak // G=specific gravity

Step 4

Determine whether your sample has cleavage. Does your mineral have cleavage?

Yes No

Step 5

Use chart below to determine your mineral:

Mineral	Description
Orthoclase potassium feldspar KalSi3O8	Variable color, most are creamy white or pinkish H: 6 G: 2.5 C: 2 good at nearly right angles L: vitreous or pearly
Plagioclase K-spar NaAlSi3O8 to CaAl2Si2O8	Creamy white or gray in color H: 6 G: 2.6-2.8 C: 2 good at nearly right angles L: vitreous or pearly striations on cleavage faces

H=hardness // F=fracture // L=luster // S=streak // G=specific gravity

Step 5

Use chart below to determine your mineral:

Mineral	Description
Quartz SiO2	Variable in color May occur as 6-sided crystals H: 7 G: 2.7 S: reddish brown L: translucent to milky Conchoidal fracture Varieties: milky (white and opaque), smoky (gray to black), rose (pink), amethyst (purple)

H=hardness // F=fracture // L=luster // S=streak // G=specific gravity

Step 5

Use chart below to determine your mineral:

Mineral	Description
Fluorite CaF2	Variable color (yellow, blue, green, or purple) H: 4 G: 3.2 C: 4 perfect, triangular cleavage faces L: transparent to translucent cubic crystals
Dolomite CaMg(CO3)2	White, gray or pink in color H: 3.5-4 G: 2.8 C: rhombohedral, 3 directions Reacts with HCl is powdered
Barite BaSO4	Clear, milky white, or light-yellow in color H: 3 G: 4.5 heavy C: 2 directions at right angles Forms thick plates
Calcite CaCO3	Variable in color H: 3 G: 2.7 C: 3 perfect; rhombohedral Reacts with HCl
Halite NaCl	Clear or milky white in color H: 2.5 G: 2.2 C: perfect cubic Tastes salty Soluble in water
Muscovite KAl2(AlSi3O10)(OH)2	Colorless to slightly gray in color H: 2-2.5 G: 2.5-3 C: 1 perfect direction Occurs in thin, transparent elastic sheets
Gypsum CaSO4 2H2O	Colorless to white in color H: 2, easily scratched with fingernail G: 2.3 C: 1 perfect, 2 good splits into slabs Varieties: selenite (colorless), satin spar (fibrous, silky), alabaster (aggregates of small crystals)
Talc Mg3Si4O10(OH)2	White, gray, green, pink, or brown in color H: 1, easily scratched with a fingernail G: 2.7 C: 1 perfect L: pearly or greasy Has a soapy feel

H=hardness // F=fracture // L=luster // S=streak // G=specific gravity