acicular

/əˈsɪkjələr/

adjective

(chiefly of crystals) needle-shaped.

The acicular crystals are sometimes intergrown or twinned, causing a distortion that results in seemingly single crystals with relatively fat bases tapering to pointed terminations.

sharp,spearlike,needle-like,spear-shaped,V-shaped,tapering,tapered,cone-shaped,conic,conical,acute,sharp-cornered,wedge-shaped,sharp-edged,edged,jagged,spiky,spiked,barbed