Acicular (crystal habit)

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Natrolite showing 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. Complete, undamaged acicular specimens can be uncommon.


Minerals with an acicular habit include mesolite, natrolite,[1] malachite, gypsum, rutile, brochantite, bultfonteinite and dimethyltryptamine.[2]

Differences from other habits[edit]

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.

See also[edit]

Needle-shaped acicular millerite crystals on white quartz


  1. ^ Hamilton, W.R. et al. (1974) The Hamlyn Guide to Minerals, Rocks and Fossils, London, Hamlyn, page 9.
  2. ^ Bergin, Rolph. et al. (1968) Preliminary X-ray Crystallographic study of some psychoactive indole bases, Stockholm, Karolinska Institutet, page 1

External links[edit]