Fractures or powders easily under pressure without deformation.
Exhibit a distinct hue (idiochromatic or allochromatic).
Lacking any intrinsic or external coloration.
Allows the flow of electric current.
Lacks reflective lustre; earthy or matte appearance.
Susceptible to nuclear fission.
Emits light immediately after UV or X-ray excitation.
Highly resistant to the flow of electric current.
Emits light after excitation by an energy source.
Responsive to external magnetic fields or exhibiting permanent magnetism.
Surface sheen typical of metals or sulfides.
Completely blocks light transmission.
Continues to emit light after the excitation source is removed.
Generates an electric charge in response to mechanical stress.
Generates an electric charge in response to temperature changes.
Emits ionizing radiation due to unstable isotopes.
Exhibits electrical conductivity between a conductor and an insulator.
Reflective or lustrous surface.
Specimen created in a laboratory rather than by geologic processes.
Light passes through but objects cannot be clearly seen.
Completely clear, allowing light and images to pass through.
Physical diagnostic traits used for the identification of mineral specimens.