Rocks and Minerals Identification Categories

Hardness

"A mineral's [] is a measure of its relative resistance to scratching, measured by scratching the mineral against another substance of known [] on the Mohs [] Scale. This graphic outlines the index minerals and some common objects that are used to determine a mineral's []." From www.nps.gov.

SG

The density of a substance relative to water. Ex. Ulexite's is 1.96, meaning that the mineral is 1.96 times heavier than water.

Streak

A description of the mark left by rubbing the specimen briefly in one straight line and direction. This is the powdered form of the mineral. Ex. White, or Pale green

Fracture

"...[The] property of a mineral breaking in a more or less random pattern with no smooth planar surfaces. Since nearly all minerals have an orderly atomic structure, individual mineral grains have internal axes of length, width, and depth, related to the consistent arrangement of the atoms." From www.maine.gov.

Tenacity

A measure mineral's resistance to breaking and bending, or being improperly shaped somehow.

Luster

The quality of shine of a specimen due to reflected light. Ec. Metallic, dull.

Chemical Structure

"...[T]he proportions of the different elements and groups of elements in the mineral." From www.appstate.edu.

Color

The hue reflected off a specimen based on the composition and chemical elements of the minerals making up a rock or the minerals themselves. This property can also help determine a mineral's density, with darker being heavier and lighter being lighter. Ex. Brown-red, colorless.

Crystal System

A set of axes or an ordered array of atoms, ions, or molecules.