Stalactitic – Forming as stalactites or stalagmites; cylindrical or cone-shaped. Their cross-sections often reveal a “concentric” pattern
Common examples include: calcite, chrysocolla, goethite, malachite
Rosette/Lenticular – Platy, radiating rose-like aggregate (also lens shaped crystals)
Common examples include: gypsum, baryte, calcite
Reticulated – Crystals forming net-like intergrowths
Common examples include: cerussite
Radial/Radiating/Divergent – Radiating outward from a central point without producing a star (crystals are generally separated and have different lengths)
Common examples include: atacamite, stibnite
Plumose – Fine, feather-like scales
Common examples: aurichalcite, boulangerite, mottramite
Platy – Flat, tablet-shaped, prominent pinnacoid
Common examples include: wulfenite
Pisolitic – Rounded concentric nodules often found in sedimentary rocks. Much larger than oolithic
Common examples include: bauxite, gibbsite
Oolithic – Small circumferences or grains (commonly flattened) that resemble eggs
Common examples include: aragonite, calcite
Hopper – Like cubic, but outer portions of cubes grow faster than inner portions creating a concavity
Common examples include: halite, calcite, synthetic bismuth A hopper crystal is a form of crystal, the shape of which resembles that of a pyramidal hopper container. The edges of hopper crystals are fully developed, but the interior spaces are not filled in. This results i
Granular – Aggregates of diminute anhedral crystals in matrix or other surface
Common examples include: andradite, bornite, scheelite, quartz
Foliated/Micaceous/Lamellar – Layered crystal structures, parting into thin sheets
Common examples include: muscovite, biotite, lepidolite, molybdenite
Filiform or capillary – Hair-like or thread-like, extremely fine
Common examples include: many zeolites, byssolite, millerite, okenite
Fibrous (including asbestiform) – Extremely slender prisms, muscle-like fibers
Common examples include: serpentine group, actinolite, kyanite, gypsum, nitratine, tremolite (i.e. asbestos) Asbestiform is a crystal habit. It describes a mineral that grows in a fibrous aggregate of high tensile strength, flexible, long, and thin crystals that readily separate. The most
Druse, encrustation – Aggregate of crystals coating a surface or cavity, usually found in geodes
Common examples: azurite, celestine, calcite, uvarovite, malachite, quartz In geology, druse refers to a coating of fine crystals on a rock fracture surface or vein or within a vug or geode. See also References
Dendritic, Arborescent – Tree-like, branching in one or more direction from central point
Common examples include: romanechite, magnesite, native copper
Coxcomb – Aggregated flaky or tabular crystals closely spaced.
Common examples include: barite, marcasite