Lustre and Habit

Lustre: Lustre refers to the sheen on the surface of a mineral or gemstone. The lustre of minerals varies and the main descriptions used by geologists are:

Vitreous: glass like.
Adamantine: like a diamond.
Resinous: a sticky substance.
Pearly: looking like pearls.
Silky: with an irregular, needle-like pattern under the surface.
Greasy: moist or slimy to the touch.
Earthy: like soil.

Habit: This scientific term describes how minerals look in their natural state. The main descriptions are:

Acicular: in needle-like shapes.
Bladed: formed in knife-like blades.
Dendritic: in branching, tree-like forms.
Lamellar: in thin, flat sheets.
Massive: in great lumps, with no particular shape.
Reniform: in kidney-shaped forms.
Tabular: in solid, flat tablets.