snowflake obsidian vs black obsidian properties

Obsidian has a long history as it has been dated back to the Stone Age, when it was used for tool making and as an ornamental stone. Obsidian is not made of mineral crystals therefore, it is not a true rock. Pliny's Natural History features volcanic glass called 'Obsidianus', so named from its resemblance to a stone found in Ethiopia by one Obsius. Tektites were once thought by many to be obsidian produced by lunar volcanic eruptions, though few scientists now adhere to this hypothesis. Obsidian has low water content when fresh, typically less than 1% water by weight, but becomes progressively hydrated when exposed to groundwater, forming perlite. This breakdown of obsidian is accelerated by the presence of water. 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. Obsidian consists mainly of SiO2 (silicon dioxide), usually 70% or more.Ĭrystalline rocks with obsidian's composition include granite and rhyolite.

Though obsidian is usually dark in color similar to mafic rocks such as basalt, obsidian's composition is extremely felsic. It is sometimes classified as a mineraloid. 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. Smoky quartz usually has a splotchy or zoned distribution to its color while Obsidian's color is more uniformly distributed. The piezoelectric and optical properties in quartz are thus absent in obsidian. However, many properties dependant on a crystal structure are altered or absent in obsidian because it lacks any crystal structure of its own. Often confused with smoky quartz, obsidian has similar properties to quartz because of a similar chemistry. Small nuggets of obsidian that have been naturally rounded and smoothed by wind and water are called Apache Tears. Inclusions of small, white, radially clustered crystals of cristobalite in the black glass produce a blotchy or snowflake pattern producing Snowflake Obsidian. These bubbles can produce interesting effects such as a golden sheen, known as Sheen Obsidian or a rainbow sheen called Rainbow Obsidian. Obsidian can contain small bubbles of air that are aligned along layers created as the molten rock was flowing just before being cooled. Iron and magnesium give the obsidian a dark green to black color. This process produces a glassy texture in the resulting rock. Often the lava pours into a lake or ocean and is cooled quickly. Obsidian is the result of volcanic lava coming in contact with water. Uses: As a semiprecious stone and ornamental stone for carvings.ĬLICK HERE To Purchase Kidz Rocks Obsidian Products. Utah: major source of snowflake variety.Chemistry: SiO2 Mostly silicon dioxide with large amounts of impurities.Wyoming: at Yellowstone National Park in particular.Oregon: varieties of fire, mahogany, and rainbow are known.

Where can obsidian be found in the United States? Iridescence noted: gold, silver, blue, violet, green, and combinations of these colors, due to inclusions of minute bubbles that reflect light.

Colors: Black gray, banded with brown streaks.Varieties: Apache Tears, Fire Obsidian, Mahogany Obsidian, Rainbow Obsidian, Sheen Obsidian, Snowflake Obsidian.

It’s classified as a mineraloid sometimes. Obsidian is mineral-like, but not a real mineral because it is not crystalline as a glass moreover, its composition is too variable to be classified as a mineral. It is commonly found within the margins of rhyolitic lava flows known as obsidian flows, where the chemical composition (high silica content) gives rise to a high viscosity that forms a natural lava glass after rapid cooling. Obsidian is produced by rapidly cooling felsic lava extruded from a volcano with minimal growth in crystals.

Snowflake obsidian vs black obsidian properties