Mineral 2

Biotite for virtual mineral identification, photograph by Sean C. Murphy, 2020.

Specimen dimensions: 4 x 2½ x ½ inches ( 100x65x15mm)

Specimen weight: 7⅛ ounces (205 grams)

Collection: Highland Campus


For reference: the U.S. penny is 0.75 inches [19.05 mm] in diameter.

Distinguishing Properties (click this to reveal) - make your list of observations before peeking

Distinguishing Physical Properties:

  • Note the Color: this is a dark, black to brownish colored mineral

  • Cleavage: the razer blade is a clue - this is what's called a platy mineral, you can peel off the layers in sheets, this means it has one "perfect" direction of cleavage

  • Appearance: perfect cleavage results in mineral peeling into thin, flexible sheets, sometimes thick specimens are called "books" because it looks like one could open the pages

  • what you can't tell from the photograph is the hardness, this mineral is soft, it can be scratched with a copper penny, perhaps even your fingernail