is created by David Witten, a mathematics and computer science student at Vanderbilt University. For more information, see the "About" page.


What is a mineral?

A mineral is a:

  • Naturally occuring

  • inorganic solid
    that possesses

  • an orderly crystalline structure
    and a 

  • definite chemical composition.

(It's important to know all four bullet points)

What is a rock?

A rock is any solid mass of mineral or mineral-like matter that occurs naturally as part of our planet. 

Seven Primary Diagnostic Properties:

  1. Crystal form: Cube, hexagonal prism, etc.
  2. Luster: Shiny? Dull?
  3. Color: Red, green, blue, etc.
  4. Streak: Scrape color on porcelain plate
  5. Hardness: Mohs scale Talc < Feldspar < Diamond
  6. Fracture or cleavage: Angle of crack
  7. Specific gravity: Density of rock/ density of water

Note about fracture vs. cleavage

Fracture- Break glass -> weird cut, not uniform

Cleavage- Break a mineral -> cleanly, uniformly breaks


Secondary Diagnostic Properties:

Taste, magnetism, malleability, feel, elasticity, smell, chemical reaction to HCl, and double refraction

Top 8 Elements that make up rocks (on Earth)

  1. Oxygen
  2. Silicon
    Know the first two, they make up 70% of all rocks
  3. Aluminum
  4. Iron
  5. Calcium
  6. Sodium
  7. Potassium
  8. Magnesium

Rock Cycle

This has one omission, which is that metamorphic rock may be exposed to MORE heat and pressure, becoming another metamorphic rock.

David Witten

Igneous Rocks

Lengths of days and years of the planets