|  Jadeite & Jade jewelry | |
| Obsidian beads |
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| Pliny's Natural History features volcanic glass called "Obsidianus", so named from its resemblance to a stone found in Ethiopia by one Obsius. Obsidian is mineral-like, but not a true mineral because as a glass it is not crystalline; in addition, its composition is too complex to comprise a single mineral. It is sometimes classified as a mineraloid. Though obsidian is dark in color similar to mafic rocks such as basalt, obsidian's composition is extremely felsic. Obsidian consists mainly of SiO2 (silicon dioxide), usually 70% or more. Crystalline rocks with obsidian's composition include granite and rhyolite. Because obsidian is metastable at the Earth's surface (over time the glass becomes fine-grained mineral crystals), no obsidian has been found that is older than Cretaceous age. This breakdown of obsidian is accelerated by the presence of water. Obsidian has low water content when fresh, typically less than 1% water by weight, but becomes progressively hydrated when exposed to groundwater, forming perlite. Tektites were once thought by many to be obsidian produced by lunar volcanic eruptions, though few scientists now adhere to this hypothesis. Pure obsidian is usually dark in appearance, though the color varies depending on the presence of impurities. Iron and magnesium typically give the obsidian a dark green to brown to black color. A very few samples are nearly colorless. In some stones, the inclusion of small, white, radially clustered crystals of cristobalite in the black glass produce a blotchy or snowflake pattern (snowflake obsidian). It may contain patterns of gas bubbles remaining from the lava flow, aligned along layers created as the molten rock was flowing before being cooled. These bubbles can produce interesting effects such as a golden sheen (sheen obsidian) or a rainbow sheen (rainbow obsidian). |
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OBS08 Obsidian beads strand, faceted ball, sold per 15-16 inches strand
$2.74 - $4.10
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OBS09 Obsidian beads strand, heart, sold per 15-16 inches strand
$1.83 - $2.73
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OBS10 Obsidian beads strand, 9*13mm gourd, sold per 15.5 inches strand
$2.93 - $4.37
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OBS11 Obsidian beads strand, 4*8mm rondelle, sold per 15.5 inches strand
$2.93 - $4.37
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OBS12 Obsidian beads strand, rice, sold per 15.5 inches strand
$2.93 - $4.37
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OBS14 Obsidian beads strand, faceted octagon, sold per 15.5-16 inches strand
$3.66 - $5.46
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OBS15 Obsidian beads strand, puff round, sold per 15-16 inches strand
$1.46 - $2.18
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OBS16 Obsidian beads strand, flat oval, sold per 15-16 inches strand
$2.74 - $4.10
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XHS01 round snowflake obsidian strand beads wholesale
$1.48 - $2.21
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| Displaying 1 to 9 (of 9 products) |
Result Pages: 1 |
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