pinacoid

American  

[pin-uh-koid] / ˈpɪn əˌkɔɪd /

noun

Crystallography.

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

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Other Word Forms

• pinacoidal adjective

Etymology

Origin of pinacoid

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

Example Sentences

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

From Encyclopaedia Britannica, 11th Edition, Volume 7, Slice 7 "Crocoite" to "Cuba" by Various

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

From Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross" by Various

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

From Encyclopaedia Britannica, 11th Edition, Volume 2, Slice 2 "Anjar" to "Apollo" by Various

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

From Encyclopaedia Britannica, 11th Edition, Volume 7, Slice 7 "Crocoite" to "Cuba" by Various

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

From Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 5 "Cat" to "Celt" by Various