Mineral Aggregate Habit
Mineral aggregates are minerals whose crystals come in groups of at times literally thousands of crystals intimately intergrowing to form unique aggregate shapes. In most cases such minerals had to form under space restriction, crowding in an intergrowing mass of small crystals. The type and habit of aggregation is often diagnostic of a specific mineral species and a strong clue to its identity.
Native Copper Cu
Dendritic Habit
Dendritic aggregates form in slender, divergent, plant- or tree-like branches
Size: 10 cm
Stibnite Sb2S3
Acicular Habit
Needle-like, slender crystals.
Size: 15 cm
Pectolite Aggregate NaCa2(HSi3O9)
Radiating Habit
Fibrous Pectolite crystals grew outward from a central point
Size: 8 cm
Pyrite “Dollar”
Coal measures near Sparta, Illinois, USA
Size: 8cm
Resembling a fossil sand dollar (echinoid), this is a pyrite concretion in its natural radiating crystal form formed in the thin beds of black shale where the pyrite crystal grows outward in only two dimensions from the centre nucleus.
Hematite Aggregate Fe2O3
Botryoidal Habit
A globular aggregate resembling a bunch of grapes with each round mass consisting of radiating small crystals
Size: 10 cm (left), 13cm (right)
Hematite Aggregate Fe2O3
Micaceous Habit
Minerals that split into very thin sheets have a micaceous Habit
Size: 12 cm