Jasper
Jasper is usually considered as Chalcedony; sometimes, however, scientists put it in a group by itself within the quartz group because of its grainy structure.
The name jasper is derived from the Greek and means "spotted stone".
The finely grained, dense jasper contains up to 20 percent foreign materials, which determine its colour, streak, and appearance. Uniformly colored jasper is rare, usually it is multicolored, striped, or flamed. Sometimes jasper can be grown together with agate or opal. There is also some fossilized material.
The name jasper is derived from the Greek and means "spotted stone".
The finely grained, dense jasper contains up to 20 percent foreign materials, which determine its colour, streak, and appearance. Uniformly colored jasper is rare, usually it is multicolored, striped, or flamed. Sometimes jasper can be grown together with agate or opal. There is also some fossilized material.
| General Information | ||||||||||||||||||||||||||||||||||||
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| A variety or type of: | Chalcedony, which is a variety of Quartz | |||||||||||||||||||||||||||||||||||
| Varieties/Types: | Dallasite - A variety of Jasper from Vancouver Island, British Columbia, Canada. Orbicular Jasper - Jasper containing numerous spherical inclusions. | |||||||||||||||||||||||||||||||||||
| Chemical Formula |
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| Jasper Treatments | ||||||||||||||||||||||||||||||||||||
| Dyed blue to imitate lapis, "Swiss lapis": lack of pyrite inclusion, chelsea - greenish-blue to red - Blue Chart Gem Identification, Herve Nicolas Lazzarelli, 2010, p 7 | ||||||||||||||||||||||||||||||||||||
| Physical Properties of Jasper | ||||||||||||||||||||||||||||||||||||
| Mohs Hardness | 6.5 to 7, Blue Chart Gem Identification (2010) | |||||||||||||||||||||||||||||||||||
| Specific Gravity | 2.58 to 2.91, Blue Chart Gem Identification (2010) More from other references | |||||||||||||||||||||||||||||||||||
| Cleavage Quality | None, Gemstones of the world (2001) | |||||||||||||||||||||||||||||||||||
| Fracture | Conchoidal,Splintery, Gemstones of the world (2001) | |||||||||||||||||||||||||||||||||||
| Optical Properties of Jasper | ||||||||||||||||||||||||||||||||||||
| Refractive Index | 1.540 (+/-), Blue Chart Gem Identification (2010) More from other references | |||||||||||||||||||||||||||||||||||
| Optical Character | Uniaxial/+, Gemmological Tables (2004) | |||||||||||||||||||||||||||||||||||
| Birefringence | None, Gemstones of the world (2001) More from other references | |||||||||||||||||||||||||||||||||||
| Pleochroism | Absent, Gemstones of the world (2001) | |||||||||||||||||||||||||||||||||||
| Dispersion | None, Gemstones of the world (2001) | |||||||||||||||||||||||||||||||||||
| Colour | ||||||||||||||||||||||||||||||||||||
| Colour (General) | All colors, mostly striped or spotted., Gemstones of the world (2001) More from other references | |||||||||||||||||||||||||||||||||||
| Causes of Colour | Orange to red, submicroscopic to microscopic inclusions of hydrous Fe oxides, Pragmatic Spectroscopy For Gemologists (2011) | |||||||||||||||||||||||||||||||||||
| Transparency | Opaque, Blue Chart Gem Identification (2010) | |||||||||||||||||||||||||||||||||||
| Fluorescence & other light emissions | ||||||||||||||||||||||||||||||||||||
| Fluorescence (General) | None, Gemstones of the world (2001) | |||||||||||||||||||||||||||||||||||
| Crystallography of Jasper | ||||||||||||||||||||||||||||||||||||
| Crystal System | Trigonal, Gemmological Tables (2004) | |||||||||||||||||||||||||||||||||||
| Habit | Microcrystalline aggregate, Gemstones of the world (2001) | |||||||||||||||||||||||||||||||||||
| Geological Environment | ||||||||||||||||||||||||||||||||||||
| Where found: | Occurs as extensive beds of sedimentary or metamorphic origin. Jasper occurs as a cavity filling or as nodules or veins in iron ores. It occurs in altered igneous rocks and in detrital deposits. It may occur in variegated red to brown colours as a petrifying agent of wood., Gems, Sixth Edition (2006) | |||||||||||||||||||||||||||||||||||
| Further Information | ||||||||||||||||||||||||||||||||||||
| Mineral information: | Jasper information at mindat.org | |||||||||||||||||||||||||||||||||||
| Significant Gem Localities | ||||||||||||||||||||||||||||||||||||
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