Post on 02-Nov-2015
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Mineral HabitsGeology 40I. Individual* Acicular - composed of a radiating mass of slender, needle-like crystals. minerals with this habit tend to be fragile, and complete, undamaged specimens can be uncommon.
Millerite, Natrolite
Bladed - blade-like, slender and flattened, similar to grass.
|Actinolite, Kyanite
Equant - any three perpendicular axis through the crystal are more or less equal. can be used to describe rounded as well as angular crystals.
Fluorite, Galena
Tabular/Stubby/Blocky - book-like (tablets) that are thicker than platy but not as elongated as bladed.
Oligoclase, Baryte
Platy - flat, tablet-shaped, prominent pinacoid.
Wulfenite, Hematite Prismatic/Columnar - elongated, prism-like: crystal faces parallel to c-axis are well-developed. pencil-like
Tourmaline, Calcite
Capillary/Filiform - hair-like or thread-like, extremely fine
Millerite, Pyrite
Striated - not a habit per se, but a condition of lines that can grow on certain crystal faces on certain minerals.
Tourmaline, SpodumeneII. Aggregate Amygdaloidal almond-shaped, bubble-shaped cavities that have become filled with minerals.
Calcite, Epidote
Fibrous - aggregates of parallel or radiating slender fibers. extremely slender prisms.
Rutilated Quartz, Silver
Botryoidal - resembling grape bunches with interlocking rounded masses.
Hematite, Sphalerite Mammillary - rounded, literally "breast-like" masses, similar to botryoidal and globular but more rounded, larger individual masses.
Chalcedony, Malachite
Globular - bubbly, rounded masses, similar to botryoidal or mammillary but less coherent.
Fluorite, Wavellite
Reniform - "kidney form" - each globular structure has an internally radiating form.
Hematite, Malachite Radiating/Divergent - growing outward from a point in sprays or starbursts. distinct crystals arranged in an orientation outward from a common point.
Pyrite Sun, Adamite
Reticulated - crystals forming net-like intergrowths.
Cerussite, Rutile
Roseiform/Rosette/Lenticular - tabular or bladed crystals in a cluster. can also be radiating rose-like aggregate.
Baryte, Gypsum Drusy/Druzy - aggregate of minute crystals coating a surface or cavity (geode).
Azurite, Amethyst
Dendritic/Arborescent - tree-like, branching in one or more direction from central point.
Pyrolusite, Copper
Foliated/Lamellar/Micaceous - layered structure, parting into thin sheets.
Lepidolite, Talc Massive/Compact - no crystal structure visible, though the mineral may be crystalline. some massive minerals may also be granular. shapeless, no distinctive external crystal shape.
Turquoise & Quartz, Forsterite & Magnetite
Granular - aggregates of anhedral crystals in matrix. crystals of a small size, less than 1 cm across, that exhibit no really discernable crystal form.
Bornite, Pyroxene & Omphacite
Banded - parallel layers of same mineral with different colors.
Rhodochrosite, Goethite
Oolitic - rounded pebble to sand sized nodules (