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Jet is around 75% carbon and 12% oxygen with sulfur and hydrogen making up most of the balance. [7] Other elements are found at trace level and the exact ratios varying with the source; for example, Spanish jet contains more sulfur than Whitby jet. [7] Jet has a Mohs hardness ranging between 2.5 and 4 and a specific gravity of 1.30 to 1.34
Agate. Agate is a fibrous, banded variety of chalcedony that occurs in a variety of colors and patterns. [9] Iris agate shows exceptional iridescence when light (especially pinpointed light) is shone through the stone. Landscape agate is chalcedony with a number of different mineral impurities making the stone resemble landscapes. [10]
Agate (/ ˈ æ ɡ ɪ t / AG-it) is a fibrous, banded variety of chalcedony. [1] Agate stones are characterized by alternating bands of different colored chalcedony and sometimes include macroscopic quartz. They are common in nature and can be found globally in a large number of different varieties.
[4] [9] Chrome chalcedony (unlike chrysoprase) may also contain tiny black specks of chromite. [3] Chrome chalcedony is (together with agate, carnelian, chrysoprase, heliotrope, onyx and others) a variety of chalcedony. This is a cryptocrystalline form of silica, consisting of fine intergrowths of the minerals quartz and moganite. [1]
Actinolite. Nephrite (var.); Adamite; Aegirine; Afghanite; Agrellite; Algodonite; Alunite; Amblygonite; Analcime; Anatase; Andalusite. Chiastolite; Andesine ...
Shades of black, or off-black colors, are colors that differ only slightly from pure black. These colors have a low lightness. From a photometric point of view, a color which differs slightly from black always has low relative luminance. Colors often considered "shades of black" include onyx, black olive, charcoal, and jet.
Onyx is a variety of quartz analogous to agate and other crypto-crystalline species. It is composed of different layers of variously colored chalcedony much like banded agate in structure, but the layers are in even or parallel planes. This makes it well adapted for the cutting of cameos and was much used by the ancients for that purpose.
If Sardonyx is a variant of onyx with red bands "rather than black" then that implies onyx has black bands, contradicting the previous sentence. 192.82.6.31 02:57, 22 July 2007 (UTC) I have an onyx, wich is black, but this may be an impurity in the stone. 88.105.63.28 13:53, 2 April 2009 (UTC) It is a bit confusing.