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Jasper, an aggregate of microgranular quartz and/or cryptocrystalline chalcedony and other mineral phases, [1] [2] is an opaque, [3] impure variety of silica, usually red, yellow, brown or green in color; and rarely blue. The common red color is due to iron(III) inclusions. Jasper breaks with a smooth surface and is used for ornamentation or as ...
A rough specimen of bloodstone. Heliotropes (from Ancient Greek ἥλιος (hḗlios) 'sun' and τρέπειν (trépein) 'to turn') (also called ematille, Indian bloodstones, or simply bloodstones) are aggregate minerals, and cryptocrystalline mixture of quartz that occurs mostly as jasper or sometimes as chalcedony (translucent).
Streak plates with pyrite (left) and rhodochrosite (right). The streak of a mineral is the color of the powder produced when it is dragged across an unweathered surface. Unlike the apparent color of a mineral, which for most minerals can vary considerably, the trail of finely ground powder generally has a more consistent characteristic color, and is thus an important diagnostic tool in mineral ...
Biggs jasper is a variety of the mineral jasper. It is a "picture jasper" – a jasper that exhibits particular patterns and colors – and is used as an opaque gemstone . [ 1 ] It exhibits intricate, shell- or layer-like patterns in shades of brown ranging from beige to dark brown.
Color is a secondary identifier for the cryptocrystalline minerals, although it is a primary identifier for the macrocrystalline varieties. [ 32 ] The most important microstructure difference between types of quartz is that of macrocrystalline quartz (individual crystals visible to the unaided eye) and the microcrystalline or cryptocrystalline ...
The name comes from the greenish color and smooth or scaly appearance from the Latin serpentinus, meaning "snake-like". Serpentine subgroup is a set of common rock-forming hydrous magnesium iron phyllosilicate ((Mg,Fe) 3 Si 2 O 5 4) minerals, resulting from the metamorphism of the minerals that are contained in mafic to ultramafic rocks. [6]
Jaspillite (or jaspilite), also called itabirite or jasper taconite, is a chemical rock formed similar to chert, but is generally quite iron-rich. Jaspillite is typically a banded mixture of hematite and quartz common in the banded iron formation rocks of Proterozoic and Archaean age in the Canadian Shield .
Specific gravity, streak (streak color and mineral hardness) and X-ray powder diffraction are quite specific for a Nickel-Strunz identifier (updated 9th ed.). Nowadays, non-destructive electron microprobe analysis is used to get the empirical formula of a mineral.