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: Jasper

Jasper used in Jewelry

Rough & Polished Jasper

Source: Egypt, Germany, Madagascar, Mexico, USA (Oregon, Idaho, Utah, Wyoming, Washington)

The name "jasper" means "spotted stone", and is derived from the Anglo-French word jaspre, and from the Greek word iaspis. Jasper is a fine-grained, totally opaque cryptocrystalline form of quartz rock, containing various shades of red, sienna, or green due to mineral impurities such as clay (white), hematite (brownish-red), and goethite (yellow).

Jasper can contain various types of patterns and/or color variations due to the formation process and is categorized as a tectosilicate. These pattern variations are created from the flow patterns in the sediments or volcanic ash saturated with silica which percolates through rock forming the jasper. Many of the so-called "picture jaspers" or "Picasso jaspers" can be brecciated, meaning that they are composed of angular fragments. Imperial jaspers can have an orbicular banding pattern that contains distinct "orbs" or spherical zones.

Imperial Jasper Cabochon

Imperial jasper cabochon (Northern Mexico)

   Morrisonite Jasper

Multcolored morrisonite jasper (Oregon)

There is such a wide variety of flow patterns, yield bands, stiations, channels, or eddying swirls in the rock's structure, varying significantly from location to location, that each type/location has its own name. These include: Biggs Blue Jasper (Oregon), Carrasite (Oregon), Dendritic Jasper, Flame Jasper, Guadalupe Poppy Jasper (California), Imperial Jasper (Northern Mexico), Leopard Skin jasper, Morrisonite Jasper (Oregon), Ocean Jasper (Madagascar), Orbicular jasper, Owyhee Jasper, Picasso jasper, Poppy Jasper (Morgan Hill, Ca), Rainbow Jasper, Red River Jasper, Rhyolite Rainforest Jasper (Australia), Sagebrush Jasper (Wyoming) and Spider Web (Black Veined) Jasper (Northern Mexico), and the list goes on and on.

Tahoma Jasper Cabochon

Tahoma jasper cabochon (Washington)

   Bruneau Jasper

Bruneau jasper cabochon (Idaho)

The hue or saturation of color can vary dramatically throughout the stone. Some varieties of Jasper have been distorted and/or fractured after formation, subsequently re-bonding into discontinuous patterns due to the filling of these fractures with other minerals or materials. Jasper is commonly associated with interbedded hematite ore deposits from the Precambrian age. Jasper also occurs as a petrifying agent in fossilized wood (aka: "jasperized wood") and bone.

Jasper belongs to the tectosilicate quartz family of minerals that include chalcedony, agate, carnelian and onyx. Jasper is typically associated with igneous rock, grown in pegmatites and geodes that formed during the mountain-building process.

Jasper (Microcrystalline Quartz) Chemistry & Physical Properties

Crystal System microcrystalline
Crystal Habit cryptocrystalline
Specific gravity (SG) 2.61 - 2.70
Mohs Hardness Scale 7
Toughness good
Fracture conchoidal, uneven
Cleavage none
Streak white
Chemical Composition SiO2 (Quartz)

Jasper (Microcrystalline Quartz) Optical Properties

Optical Properties singly refractive
Refractive Index 1.486
Birefringence +0.009
Pleochroism none
Surface Luster dull to waxy
Diaphaneity translucent, sub-translucent, opaque
Gem Color brown, gray, green, red

The famous European gem cutting and polishing capital of Idar-Oberstein, in western Germany was built on a 500+ year history on mining agate, amethyst, jasper, and quartz found in basalt formations of the Hunsrčck Mountains that surround the picturesque Rhineland town. Today, the main sources for gem-quality jasper are in the western United States in the states of Eastern Oregon (Owyhee), Idaho, Utah, Wyoming and Washington State, Australia, Madagascar, and Mexico.

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Bibliography and Reference on Jasper

1. Judith Crowe, The Jeweler's Directory of Gemstones . DK Publishing.

2. A.C. Akhavan, Twinning in Quartz Crystals www.quartzpage.de

3. GIA, Characteristics of Citrine, Amethyst & Smoky Quartz www.gia.edu

4. Renee Newman, Gemstone Buying Guide . International Jewelry Publications; 2nd edition

5. Antoinette L . Matlins, Antonio C. Bonanno, Gem Identification Made Easy . Gemstone Press

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