hemimorphic


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hem·i·mor·phic

 (hĕm′ĭ-môr′fĭk)
adj.
Asymmetric at the axial ends. Used of a crystal.

hemimorphic

(ˌhɛmɪˈmɔːfɪk)
adj
(Chemistry) (of a crystal) having different forms at each end of an axis
ˌhemiˈmorphism, ˈhemiˌmorphy n

hem•i•mor•phic

(ˌhɛm ɪˈmɔr fɪk)

adj.
(of a crystal) having the two ends of an axis unlike in their planes or modifications; lacking a center of symmetry.
[1860–65]
hem`i•mor′phism, hem′i•mor`phy, n.
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References in periodicals archive ?
Hemimorphic topaz crystals (though common in the Ouro Preto deposits) and twins are unknown from Schneckenstein.
It is, at the same time, hemimorphic. Combining these two properties, we can say that the crystal with this symmetry is left-handed or right-handed, and that its "termination" is not the same as its base.
Some crystals appear hemimorphic, exhibiting pyramidal modifications on only one side of the tablet, and a larger flat c face on the other.
The crystals measure up to 10 cm and have distinctive hemimorphic habits, with one end of the hexagonal prism terminated by either {10-12} or {02-21} pyramidal faces, the other termination exhibiting bundles of elongated acicular crystals, resembling an extended trigonal "Mercedes Benz" emblem.
Crystals are typically hexagonal pyramidal and hemimorphic, in some cases with prism faces, and sometimes grouped interestingly in cyclic "tetrapod" twins on (10[bar.1][bar.2]), composed mainly of {10[bar.1]0} prism faces and {50[bar.5]3} pyramids, with tiny c-faces.
Weloganite crystals (5) are characteristically strongly striated or grooved due to pronounced oscillatory growth along [001], and most are distinctly hemimorphic. Twinning is common, as evidenced by prominent re-entrant angles along [001], and sharp angular articulations, or kinks, in smaller (less than 1 cm) weloganite crystals.
Morphologically, Barra de Salinas tourmaline crystals exhibit an overwhelming tendency to be terminated by multiple rhombohedron form rather than basal pedion (tourmaline being trigonal and hemimorphic).
When doubly terminated (as they very frequently are) the crystals display the hemimorphic nature of tourmaline-group species: on one end, a perfectly flat basal pinacoid face, with matte luster, and on the other, three rhombohedral (trigonal) faces with glassy luster.
Donnayite-(Y) is extremely rare, and is found in cavities in the contact zone as crude, equant, opaque, beige to yellowish white hemimorphic crystals 0.5-1.0 mm in size, having a roughly hexagonal to circular cross-section, and dominated by a {001} basal pinacoid.