Acicular (crystal habit)
Acicular, in mineralogy, refers to a crystal habit 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.
Differences from other habits
Some minerals like creedite form prismatic crystals that appear to be acicular, but are instead prismatic in a bladelike form; these can be told apart by the fact that all prismatic crystals are less sharp, sometimes are tipped with a pyramidal shape, and keep a standard cross-section shape with straight edges. Acicular crystals differ from fibrous crystals in their thickness; crystals with a fibrous habit are much thinner, sometimes to the point of being flexible like hair, while acicular crystals are thicker and rigid.
- Hamilton, W.R. et al. (1974) The Hamlyn Guide to Minerals, Rocks and Fossils, London, Hamlyn, page 9.
- "Skeletal microstructure of Galaxea fascicularis exsert septa: a high-resolution SEM study", Biological Bulletin
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