submetallic


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Related to submetallic: quartz

submetallic

[¦səb·mə′tal·ik]
(optics)
Referring to a luster intermediate between metallic and nonmetallic, such as exhibited by the mineral chromite.
References in periodicals archive ?
It occurs as velvety black, submetallic plates, up to 1 mm in diameter; as black hexagonal plates and rosettes; as dull black, granular patches; and as a dull black, thin coating on small rosettes of brookite.
Pseudorutile was reported to occur as black, submetallic, granular patches associated with "K-feldspar," brookite and dawsonite (Sabina, 1979).
Rutile has been identified in at least one specimen (from a sill cavity) as black, submetallic plates associated with dawsonite, calcite and quartz (GSC APS 709).
Some pyrite grains in silicified serpentinite matrix were observed to be rimmed or replaced by a black submetallic mineral.
Physical, chemical and crystallographic properties: Luster: resinous to submetallic. Diaphaneity: opaque but translucent on thin edges.
In the oxidation zone it is found in cavities in the spongy siderite ore, as opaque, black, hexagonal, tabular or short prismatic crystals 1-3 mm across, with bluish iridescence and a submetallic luster; as a crust consisting of masses of thin, bluish lamellae, 0.5-1 mm across, and as pseudohexagonal, tabular pseudomorphs after chalcocite, 0.5-2 mm across, invariably associated with unaltered chalcocite.
In some of these sulfide crusts, where tetrahedrite predominates, famatinite is found very rarely as dull black, submetallic layers and veinlets up to 0.2 mm across.
Broken surfaces exhibit a marked radial structure, steel-gray color and submetallic luster.
Anglesite is typically found as a massive silvery-black submetallic massive material in small seams and pockets throughout the vein.
Arakiite is megascopically indistinguishable from either hematolite or dixenite and possesses the following physical properties: steak is pale brown; lustre is resinous to submetallic; diaphaneity is opaque (masses) to translucent (thin edges); non-fluorescent; hardness is estimated at 3-4; cleavage is {001} perfect; tenacity is brittle; fracture is uneven, almost subconchoidal; calculated density is 3,41 g/[cm.sup.3] (for empirical formula and unit-cell parameters derived from crystal structure).
The lustre is resinous to submetallic, and masses are opaque whereas thin edges of grains are translucent.
The hematite crystals are mostly loose, horizontally striated hexagonal prisms with wavy faces (think corundum), black, with a medium-bright submetallic luster, all from 1.5 to 2.5 cm high.