pinacoid


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pinacoid

(ˈpɪnəˌkɔɪd)
n
1. (Chemistry) one of a pair of opposite parallel faces of a crystal
2. (Chemistry) a crystal that contains a pair of opposite parallel faces
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References in periodicals archive ?
While the rough material appeared dark and opaque overall, it displayed a peculiar weak golden shimmering effect on basal pinacoid surfaces.
Type I consists of columnar crystals which are simple combinations of striated {110} prism faces and flat {001} pinacoid faces.
Gmelinite is generally pink and vitreous with well formed colourless hexagonal dipyramid, prism and pinacoid crystals (Fig.
The (011} prism and the {100} pinacoid are the only important forms, but {110}, {010}, {031} and {101) are also present.
The dominant crystallographic form is the pinacoid {001} with much smaller {110} faces.
In one type, stout, color-zoned elbaite crystals to 15 cm long end in flat basal pinacoid terminations; they are green at the tips but pink through the bulk of the prisms, with some yellow bands.
The sharp-edged, well-formed crystals consist of a simple hexagonal prism terminated by the {0001} basal pinacoid.
From a prospect begun in summer 2009 at Onderra, Kaokoveld, comes wulfenite in thick, tabular orange and yellow-orange crystals to 4 cm with prominent pyramid faces (in some cases almost obliterating the normally dominant basal pinacoid faces).
5 cm, are dull milky white but textbook-sharp, composed about equally of a tetragonal prism and a tetragonal bipyramid, with small basal pinacoid faces topping (and bottoming) off the shape.
The morphology consists of a hexagonal prism and basal pinacoid modified by complex terminations consisting of up to three or four hexagonal dipyramid forms.
Habit 1 is characterized by very sharp and lustrous, short-prismatic, dark green crystals with two very narrow pyramidal faces and a dominant basal pinacoid.
The lustrous anatase crystals are fat, equant dipyramids with large basal pinacoid terminations, calling to mind the well known blue-black Norwegian crystals, except that these are a very dark brown and look jet-black under most lighting conditions.