subhedral


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subhedral

(sʌbˈhiːdrəl)
adj
(Minerals) with some characteristics of crystal
References in periodicals archive ?
2 mm in size and are euhedral to subhedral (predominant) cubes and octahedra which are tightly intergrown in some areas.
One of the dykes in the Ranpur area contains up to 8 cm long, euhedral to subhedral plagioclase phenocrysts in medium- to fine- grained matrix and another near Karai shows some layering which is unusual, considering the small size of the body.
It is very rare and occurs as irregular aggregates less than 2 mm across, of dull, opaque, pale gray subhedral crystals associated with dull white weloganite (habit G), analcime, albite, marcasite, calcite and dolomite.
Subhedral plagioclase is slightly to extensively altered to saussurite and sericite.
The diorites of the studied area are medium- to coarse-grained, equigranular to inequigranular, subhedral characterized by a common hypediomorphic granular texture.
These specimens are certainly nothing on the order of the giant, flaring groups of multicolored prisms which came from the Pederneira mine a few years ago; they are single, loose crystals, a few doubly terminated, many with the distinctive (for Pederneira) brushy clusters of purple subhedral lepidolite books around their bases.
Phenocrystic plagioclase forms euhedral to subhedral tabular crystals, ranging from 1 to 12 mm long, with rectangular cross sections and polysynthetic albite twinning.
The main primary minerals include plagioclase, clinopyroxene, orthopyroxene, amphibole and minor quartzdescribed as under: Plagioclase: Plagioclase crystals are euhedral to subhedral, lathlike and columnar in shape, and exhibit polysynthetic twinning (according to the albite and occasionally to the combined albite and Carlsbad laws) and oscillatory zoning.
In hand specimens, the coarse-grained rodingite is seen to consist of subhedral, bright green chromian diopside crystals up to about 10 cm in maximum dimension, with large pods of porcelaneous white to pink to brownish red grossular, along with accessory clinochlore, prehnite, clinozoisite and hydrogrossular.
However in this facies, K-feldspar developed as a late phase that occurs as large K-feldspar plates in normal abundance (10-20%), commonly anhedral to subhedral and wholly poikilitic to the point of being nearly invisible unless seen as a reflecting cleavage surface.
The grains of hornblende are anhedral to subhedral and mostly medium to large in size.