Jasper

Jasper

     Silicon Dioxide (SiO₂ - 80-95%, AL₂O₃ and Fe₂O₃ - up to 15%, CaO - 3-6%)
     In mineral structure there are quartz, sometimes chalcedony prevails, frequently epidote, a pomegranate, actinolite, sericite, hematite, biotite, piedmontite, pumpellite.
     Color: red, yellow, brown, green. Coloring is connected with pigmental substances: hematite - reddish tone, hematite - brown and yellow, and also the flocculent congestions of various structure giving to ore white, yellowish, gray color and porcelain shape. Dark blue color can be caused amphibole, and green - pumpellite - and chlorite. At some versions of jaspers there are dendrites the various coloring, raising their decorative effect.
     Hardness: 6 - 7 on Mohs scale.
     Density: 2.58 - 2.91 gr/sm³.
     Break: equal, smooth.
     Transparency: it is opaque.
     The name "jasper" of east origin also corresponds Persian "iashm" and "jashp", and also assyrian "ashpu". To jaspers as to ornamental stones, the big group of ores of various structure and the formation concerns, incorporated by the following attributes: siliceous structure, high hardness and decorative effect a beautiful coloring and figure. Among ornamental jasper ores there are two basic versions distinguished by structure of initial ores: actually jaspers and like jasper ores to which concern hornstones. Sometimes as jaspers consider the ore of similar shape which essential component is feldspar. The term "jasper" in application to opaque versions of quartz with red, brown, green coloring has appeared at the end of 18 - beginnings of 19 centuries. There isn't the uniform term of this word. Now in technical and geological sense the term "jasper" is understood as metamorphogenic initial sedimentary and volcanogenic-sedimentary ores, siliceous, firm, opaque, motley on coloring and combined of cryptocrystalic quartz, sometimes with an impurity of chalcedony.
     The most detailed classification of ornamental jasper ores was developed by A.E.Fersman. It is allocated six classification groups of jaspers:
     1. homogeneous, coloring red all kinds up to black, white, pink, violet, green, gray etc.;
       1a. homogeneous, with separate spots or inclusions, coloring pale-yellow, with black dendrites, with stains, jets, clouds of gentle figure, with white or black points;
     2. striped, parallel - striped, various on color and type of strips, with sharp borders (red - green), with soft transitions (red - yellow), with large (more 1sm) strips , with little (up to 1см) strips (gray - yellow, green etc.), jet with little porphyritic allocations;
     3. porphyritic with ingrowths corpuscles of feldspar, with transparent inclusions of quartz and black inclusions - augite and amphibole;
     4. multicolored, homogeneous with strips of other color (motley, different colors with one-color cement, with soft striped coloring;
     5. breccias and conglomerates - porphyritic breccias, jasper breccias, conglomerates;
     6. spheroid incrusted (agate jasper), spheroid large and little, agate, striped, layered, batteryes (protective).
     In territory of former Soviet Union it is registered more than 500 deposits of jasper ores, most of them are investigated poorly. Southern Ural is especially rich of various jaspers, ornamental jasper ores are known on Altai, Northern Caucasus, the Western Kazakhstan, Uzbekistan, Tajikistan.
     On beauty the jasper of a deposit of mountain the Colonel near to city of Orsk on Southern Ural is exclusive.
     Jasper applied to manufacturing of different art gemstones wares ( vases, ashtrays, jewelry boxes, desk sets, candelabrums, clocks etc.) and cabochons - inserts in jewelry (rings, brooches, cuff links etc.), and also a beads.

@ Copyright 2003 - 2008