pinacoid

[ pin-uh-koid ]

noun

, Crystallography.

1. a form whose faces are parallel to two of the axes.

Other Words From

• pina·coidal adjective

Word History and Origins

Origin of pinacoid¹

1875–80; < Greek pinak- (stem of pínax ) slab, board + -oid

Example Sentences

All the forms, except the prisms and basal pinacoid, are sphenoids.

From Project Gutenberg

All the closed forms are hexagonal bipyramids; the open forms are hexagonal prisms or the basal pinacoid.

From Project Gutenberg

There is an imperfect cleavage parallel to the basal pinacoid, and the fracture is conchoidal.

From Project Gutenberg

Acute rhombohedra in combination with the basal pinacoid are also frequent, giving crystals of octahedral aspect.

From Project Gutenberg

The cleavage is perfect parallel to the basal pinacoid, and less marked parallel to the prism.

From Project Gutenberg