Mineral Identification key

Directions: Use this key to identify the minerals.

1. Is the luster metallic?
   1. Yes - Metallic Luster

      Streak Color	Description	Mineral
      black, gray, or dark green streak	black, strongly magnetic, harder than glass (H=6)	Magnetite
      	gray to black, smudges fingers, shiny, slippery, softer than fingernail (H=1)	Graphite
      	shiny silver-gray, very heavy, occurs in cubes, harder than fingernail (H=2.5)	Galena
      	shiny pale yellow-gold, often in cubes, harder than glass (H=6.5)	Pyrite
      	brass yellow, weakly magnetic, same hardness as steel (H=4.5)	Chalcopyrite
      red to brown streak	red-brown to black, earthy or powdery, same hardness as glass (H=5-6)	Hematite
      	steel gray, shiny, same hardness as glass (H=5-6)	Specular Hematite

   2. No...go to 2.

2. Non-metallic Luster: Is the color dark?
   1. Yes...go to 3.
   2. No...go to 4.

3. Non-metallic Luster, Dark Color: Does the mineral scratch glass?
   1. Yes - Harder than Glass

      Cleavage or fracture?	Description	Mineral
      Cleavage	light to dark pink, blocky, 2 cleavage planes at almost 90°, harder than steel (H=6)	Orthoclase Feldspar
      	black to dark green, cleavage planes at almost 90°, same hardness as glass (H=6)	Pyroxene
      	black to dark green, cleavage planes at 60° and 120°, same hardness as glass (H=6)	Amphibole
      Fracture	gray to black, glassy, curved fracture, harder than glass (H=7)	Smokey Quartz
      	black, brown or gray, curved fracture, harder than glass (H=7)	Flint (quartz)
      	brown with some green or purple, dull, harder than glass (H=9)	Corundum
      	bright to dark green, glassy, usually in granular masses, harder than glass (H=6)	Olivine
      	black, strongly magnetic, irregular masses or chunks, harder than glass (H=6)	Magnetite

   2. No - Softer than Glass

      Cleavage or fracture?	Description	Mineral
      Cleavage	colorless, green or purple, glassy, 4 good cleavage planes, harder than penny (H=4)	Fluorite
      	black to brown, one perfect cleavage plane (basal), thin flexible sheets, same hardness as fingernail (H=2.5)	Biotite Mica
      	green, basal cleavage, platy masses or fine particles,same hardness as fingernail (H=2.5)	Chlorite
      Fracture	red to red-brown streak, earthy, softer than fingernail (H=1)	Hematite
      	green, basal cleavage, platy masses or fine particles,same hardness as fingernail (H=2.5)	Chlorite
      	gray, pink or white, greasy or soapy feel, softer than fingernail (H=1)	Talc

4. Non-metallic Luster, Light Color: Does the mineral scratch glass?
   1. Yes - Harder than Glass

      Cleavage or fracture?	Description	Mineral
      Cleavage	light to dark pink, blocky, 2 cleavage planes at almost 90°, harder than steel (H=6)	Orthoclase Feldspar
      	gray to white, blocky, 2 cleavage planes at almost 90°, harder than steel (H=6)	Oligoclase (Sodium Feldspar)
      Fracture	transparent (or almost so), glassy, curved fracture, crystals common, harder than glass (H=7)	Quartz
      	milky white, glassy, curved fracture, harder than glass (H=7)	Milky Quartz
      	pink, glassy, curved fracture, harder than glass (H=7)	Rose Quartz
      	white, yellow, gray, black, or brown, sometimes banded, dull and opaque, curved fracture, harder than glass (H=7)	Chert
      	bright to dark green, glassy, usually in granular masses, harder than glass (H=6)	Olivine

   2. No - Softer than Glass

      Cleavage or fracture?	Description	Mineral
      Cleavage	colorless, white or pale orange, forms cubes, perfect cubic cleavage, salty taste, same hardness as fingernail (H=2.5)	Halite (salt)
      	white or colorless, perfect rhombohedral cleavage (squashed cube), fizzes with acid, harder than fingernail (H=3)	Calcite
      	colorless to light yellow, one perfect cleavage plane, thin flexible sheets, same hardness than fingernail (H=2.5)	Muscovite Mica
      	white to pink, thick transparent plates or fibrous, softer than fingernail (H=2)	Gypsum
      	colorless, green, purple, yellow or brown, glassy, 4 good cleavage directions, harder than penny (H=4)	Fluorite
      Fracture	white, fibrous or granular masses, softer than fingernail (H=2)	Gypsum
      	gray, pink or white, greasy or soapy feel, softer than fingernail (H=1)	Talc
      	bright yellow, waxy luster, odor, same hardness as fingernail or slightly harder (H=1.5-2.5)	Sulfur