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Density of a mineral relative to water. Examples: Gold (high specific gravity), Quartz (moderate)

The emission of particles due to the decay of an unstable nucleus. Examples: Uraninite (radioactive), Zircon (sometimes radioactive)

Tendency of a mineral to vaporize. Examples: Mercury (high volatility), Quartz (low volatility)

Electric charge in crystals that are subject to temperature changes. Examples: Tourmaline (pyroelectric), Topaz (may show pyroelectricity)

Phenomenon where a star-shaped pattern appears in the light reflected from a gemstone. Examples: Star Sapphire, Star Ruby

The degree of transparency of a mineral. Examples: Transparent (quartz), Translucent (alabaster), Opaque (hematite)

Conductivity or resistance to electrical current. Examples: Graphite (conductor), Quartz (insulator)

The ability of a mineral to bend and return to its original shape. Examples: Mica (elastic), Quartz (brittle, non-elastic)

Light generated when a crystal is rubbed, scratched, or broken. Examples: Quartz (shows triboluminescence), Sugar (also shows often)

Resistance to breaking, crushing, or bending. Examples: Diamond (brittle), Talc (flexible)

Measure of how much light is bent when entering a mineral. Examples: Diamond (high RI), Calcite (low RI)

The ability to be drawn into a thin wire. Examples: Copper (ductile), Quartz (not ductile)

The ability to be hammered into thin sheets. Examples: Gold (malleable), Calcite (non-malleable)

Behavior with respect to light, including diffraction and polarization. Examples: Opal (diffractive), Moonstone (adularescence)

A type of photoluminescence related to fluorescence but persists in darkness. Examples: Calcite (may show phosphorescence), Zinc sulfide (often shows)

Electric charge accumulated in solid materials in response to mechanical stress. Examples: Quartz (piezoelectric), Tourmaline (also piezoelectric)

The amount of heat energy needed to raise the temperature of a substance. Examples: Quartz (low specific heat), Water (high specific heat)

Ability to dissolve in a solvent. Examples: Halite (soluble in water), Gold (insoluble)

The constant for the solubility equilibrium of a compound. $K_{sp} = [A^+][B^-]$, where $A^+$ is the cation and $B^-$ is the anion. Examples: Calcite (low Ksp), Halite (higher Ksp)

Measure of resistance to scratching, defined by Mohs scale. Examples: Talc (1), Diamond (10)

Isotropy: Equal properties in all directions. Anisotropy: Unequal properties in different directions. Examples: Garnet (isotropic), Calcite (anisotropic)

Scale of hardness ranging from 1 (talc) to 10 (diamond).

Ability of a mineral to expand when heated. Examples: Beryl (low thermal expansion), Quartz (relatively higher thermal expansion)

General shape a mineral tends to grow. Examples: Bladed (Kyanite), Fibrous (Asbestos)

Mass per unit volume. $\rho = \frac{m}{V}$, where $\rho$ is density, $m$ is mass, $V$ is volume. Examples: Lead (high density), Calcite (low density)

External geometric shape of a crystal. Examples: Halite (cubic), Quartz (hexagonal)

Temperature at which a substance changes from liquid to gas. Examples: Water (100°C), Quartz (>2230°C)

Phenomenon where a mineral appears to be different colors when viewed from different angles. Examples: Cordierite, Tanzanite

Parallel lines or grooves on cleavage surfaces. Examples: Plagioclase Feldspar (shows striations), Quartz (no striations)

Response to changes in temperature, including expansion and conductivity. Examples: Quartz (low thermal expansion), Copper (high thermal conductivity)

The tendency to break along flat planes. Examples: Mica (perfect cleavage), Feldspar (good cleavage)

Attraction to a magnetic field. Examples: Magnetite (strongly magnetic), Pyrrhotite (weakly magnetic)

Emission of light by a mineral when it is illuminated by UV light. Examples: Fluorite (glows), Calcite (can glow)

Temperature at which a mineral changes from solid to liquid. Examples: Ice (0°C), Diamond (>3500°C)

Irregular breakage not along cleavage planes. Examples: Quartz (conchoidal), Garnet (uneven)

Double refraction of light as it passes through an anisotropic mineral. Examples: Calcite (high birefringence), Glass (isotropic, no birefringence)

The color of the mineral in powdered form. Examples: Hematite (red-brown), Pyrite (black-green)

Inherent in the mineral. Examples: Malachite (green), Azurite (blue)

The way a mineral reflects light. Examples: Metallic (Galena), Non-metallic (Quartz)

Degree to which light passes through a mineral. Examples: Transparent (Calcite), Opaque (Galena)

Reaction with acids or other chemicals. Examples: Calcite (fizzes with HCl), Pyrite (no reaction)