Diffusion from a center produces a distinctive orbicular appearance, i.e., leopard skin jasper or linear banding from a fracture as seen in liesegang jasper. Such patterns include banding from flow or depositional patterns (from water or wind), as well as dendritic or color variations. Picture jaspers exhibit combinations of patterns resulting in what appear to be scenes or images, when seen on a cut section. The red bands, typically more competent than the hematite layers surrounding it, are made of microcrystalline red chert, also called jasper.Įarrings of polished "leopard-spot jasper" (actually a type of spherulitic rhyolite) Jasper is the main component in the silica-rich parts of banded iron formations (BIFs) which indicate low, but present, amounts of dissolved oxygen in the water such as during the Great Oxidation Event or snowball earths. A few are designated by the place of origin such as a brown Egyptian or red African. Terms attributed to various well-defined materials includes the geographic locality where it is found, sometimes quite restricted such as "Bruneau" (a canyon) and "Lahontan" (a lake), rivers and even individual mountains many are fanciful, such as "forest fire" or "rainbow", while others are descriptive, such as "autumn" or "porcelain". The classification and naming of jasper varieties presents a challenge. Weathering, with time, will create intensely colored superficial rinds. The original materials are often fractured and/or distorted, after deposition, into diverse patterns, which are later filled in with other colorful minerals. Jasper can be modified by the diffusion of minerals along discontinuities providing the appearance of vegetative growth, i.e., dendritic. Hydrothermal circulation is generally thought to be required in the formation of jasper. Patterns arise during the consolidation process forming flow and depositional patterns in the original silica-rich sediment or volcanic ash. Jasper is an opaque rock of virtually any colour stemming from the mineral content of the original sediments or ash.
Russian, late 19th century, Kremlin Armoury Goat-headed basket carved from red jasper. Flinders Petrie suggested that the odem, the first stone on the High Priest's breastplate, was a red jasper, whilst tarshish, the tenth stone, may have been a yellow jasper. The Hebrew word may have designated a green jasper. The jasper of the ancients probably included stones which would now be classed as chalcedony, and the emerald-like jasper may have been akin to the modern chrysoprase. Jasper is referred to in the Nibelungenlied as being clear and green. The jasper of antiquity was in many cases distinctly green, for it is often compared to emerald and other green objects. Īlthough the term jasper is now restricted to opaque quartz, the ancient iaspis was a stone of considerable translucency including nephrite. On Minoan Crete, jasper was carved to produce seals circa 1800 BC, as evidenced by archaeological recoveries at the palace of Knossos. Jasper is known to have been a favorite gem in the ancient world its name can be traced back in Arabic, Persian, Hebrew, Assyrian, Greek and Latin. Green jasper was used to make bow drills in Mehrgarh between 4th and 5th millennium BC. This Semitic etymology is believed to be unrelated to that of the English given name Jasper, which is of Persian origin, though the Persian word for the mineral jasper is also yashp ( یَشم). iaspis) from Greek ἴασπις iaspis (feminine noun), from an Afroasiatic language (cf. The name means "spotted or speckled stone," and is derived via Old French jaspre (variant of Anglo-Norman jaspe) and Latin iaspidem (nom. Low-relief sphinx pendant, red jasper, pearl and enamel, French, circa 1870 Jaspillite is a banded-iron-formation rock that often has distinctive bands of jasper. The specific gravity of jasper is typically 2.5 to 2.9. It can be highly polished and is used for items such as vases, seals, and snuff boxes.
Jasper breaks with a smooth surface and is used for ornamentation or as a gemstone. The common red color is due to iron(III) inclusions. Jasper, an aggregate of microgranular quartz and/or cryptocrystalline chalcedony and other mineral phases, is an opaque, impure variety of silica, usually red, yellow, brown or green in color and rarely blue. Most commonly red, but may be yellow, brown, green or (rarely) blue Jasper outcrop, Bucegi Mountains, Romania
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