acicular

Crystals of arsenic belong to the rhombohedral system, and have a perfect cleavage parallel to the basal plane; natural crystals are, however, of rare occurrence, and are usually acicular in habit.

From Encyclopaedia Britannica, 11th Edition, Volume 2, Slice 6 "Armour Plates" to "Arundel, Earls of" by Various

The fragments are angular or rounded, small or large, and consist of bluish or reddish compact feldspathic matter, in which a few acicular crystals of feldspar can sometimes be seen.

From Geological Observations on South America by Charles Darwin

Sammetblende or przibramite is a variety, from Przibram in Bohemia, consisting of delicate acicular or capillary crystals arranged in radiating groups with a velvety surface and yellow colour.

From Encyclopaedia Britannica, 11th Edition, Volume 12, Slice 3 "Gordon, Lord George" to "Grasses" by Various

It can readily be recognised by its acicular, needle-like leaves, and more particularly by its peculiarly shaped seed vessel, which resembles the pattern on an old-fashioned Indian shawl.

From Getting Gold: a practical treatise for prospectors, miners and students by J. C. F. (Joseph Colin Frances) Johnson

Much of the calcium in sea-water exists as sulphate; and on evaporation of a drop of sea-water under the microscope this sulphate is deposited as acicular crystals of gypsum.

From Encyclopaedia Britannica, 11th Edition, Volume 12, Slice 7 "Gyantse" to "Hallel" by Various