Earth Science Lab Midterm Review –

Rocks and Minerals –

Rocks – Igneous, Sedimentary, or Metamorphic and whyo Igneous – Intergrown or Random Crystals, or Glassy (Obsidian)

Use color and crystal size to determine specific type.

o Sedimentary – Made of Sediments or Fossils

Use sediment size (feel) to determine type. Always test with

acid in case it is limestone!

o Metamorphic – Foliation (mineral alignment, looks like thin layers) or Banding (alternating light/dark layers. Gneiss only).

Use amount of metamorphism to tell type. Remember, on Gneiss has banding!

Minerals – o Metallic – looks like Silver, Gold, or Black

w/glitter(sparkles)

o Non-metallic – Glassy, translucent, other colors.

o Cleavage – Even breaks, repeating pattern Remember – FLUORITE HAS CLEAVAGE but it is often hard to see.

o Fracture – Uneven, random breaks. Remember – QUARTS HAS FRACTURE but looks like cleavage because of the crystal shape.

Try to ID the mineral, and use the ESRT to help you identify cleavage vs fracture

o Hard – scratches glassOR

o Soft – Doesn’t scratch glass

o Colored/Dark Streak OR

o White/No Streak