Tumbled Black Obsidian Stone 0.5 to 8 g small size pieces 200 gram Lot

Description

Well tumbled Natural Black Obsidian  Stone (small to medium size pieces)
- 0.2 Kg Lot (0.44 pound)
Weight per piece: 0.5 to 8 gram
Sizes:  6x7x11 mm to 15x20x27 mm (0.2x0.3x0.5 to 0.6x0.8x1.1 inch)
Quantity: about 36 to 75 pieces in each lot
These stones are from Africa.
The pictures in the listing are just for reference as we are selling multiple pieces with same pictures.
***
Obsidian
Category  Volcanic glass
Chemical formula  70–75% SiO2, plus MgO, Fe3O4
Color  Black
Fracture  Conchoidal
Allaboutlearning
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Tumbled Black Obsidian Stone 0.5 to 8 g small size pieces 200 gram Lot
Well tumbled Natural
Black Obsidian
Stone
(small to medium size pieces)
- 0.2 Kg Lot (0.44 pound)
Weight per piece: 0.5 to 8 gram
Sizes:  6x7x11
mm to 15x20x27 mm (0.2x0.3x0.5 to 0.6x0.8x1.1 inch)
Quantity: about 36 to 75 pieces in each lot
These stones are from Africa.
The pictures in the listing are just for reference as we are selling multiple pieces with same pictures.
***
Obsidian
Category  Volcanic glass
Chemical formula  70–75% SiO2, plus MgO, Fe3O4
Color  Black
Fracture  Conchoidal
Mohs scale hardness  5–6
Luster  Vitreous
Specific gravity  ~2.4
Optical properties  Translucent
Obsidian
is a naturally occurring volcanic glass formed as an extrusive igneous rock.
It is produced when felsic lava extruded from a volcano cools rapidly with minimum crystal growth. Obsidian is commonly found within the margins of rhyolitic lava flows known as
obsidian flows
, where the chemical composition (high silica content) induces a high viscosity and polymerization degree of the lava. The inhibition of atomic diffusion through this highly viscous and polymerized lava explains the lack of crystal growth. Obsidian is hard and brittle; it therefore fractures with very sharp edges, which had been used in the past in cutting and piercing tools, and are still used as surgical scalpel blades.
Obsidian is the rock formed as a result of cooled magma, which is the parent material. Having a low water content when newly formed typically less than 1% water by weight, 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.
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 usually 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.
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 brown to black color. 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 an iridescent, rainbow-like sheen (
rainbow obsidian
).
Obsidian can be found in locations which have experienced rhyolitic eruptions.
Item Specifics
Total Carat Weight (TCW)
1000
Natural/Lab-Created
Natural
Color
Black
Shape
Rough
Treatment
Not Enhanced
Brand
Unbranded
Country/Region of Manufacture
China
Carat Range
Greater than 6.00
Transparency
Opaque
Country of Origin
China
Modified Item
No
Payment
Payment: By Paypal
Shipping cost
Free shipping cost.
We send the goods to USA, Canada, UK, Australia, New Zealand, EU countries and some other European and Asian countries by E-express, a kind of fast postal service by Hong Kong Post. It usually takes about 6 to 10 working days for delivery.
We send the goods to other countries by registered airmail and will take about 8 to 14 working days for delivery.
Return policy
Returns: We accept returns with any reason in 30 days. Buyer will bear the return shipping cost.
Messages
We will answer messages in 24 hours during working days.
[ Policy
: This is the contents of your policies. You can add a banner for this policy as header and add text descriptions here. The text descriptions can be different Font Size, Font Color, Style and even graphics and icons are also accepted. ]
Allaboutlearning
Your best online business partner
Tumbled Black Obsidian Stone 0.5 to 8 g small size pieces 200 gram Lot
Well tumbled Natural
Black Obsidian
Stone
(small to medium size pieces)
- 0.2 Kg Lot (0.44 pound)
Weight per piece: 0.5 to 8 gram
Sizes:  6x7x11
mm to 15x20x27 mm (0.2x0.3x0.5 to 0.6x0.8x1.1 inch)
Quantity: about 36 to 75 pieces in each lot
These stones are from Africa.
The pictures in the listing are just for reference as we are selling multiple pieces with same pictures.
***
Obsidian
Category  Volcanic glass
Chemical formula  70–75% SiO2, plus MgO, Fe3O4
Color  Black
Fracture  Conchoidal
Mohs scale hardness  5–6
Luster  Vitreous
Specific gravity  ~2.4
Optical properties  Translucent
Obsidian
is a naturally occurring volcanic glass formed as an extrusive igneous rock.
It is produced when felsic lava extruded from a volcano cools rapidly with minimum crystal growth. Obsidian is commonly found within the margins of rhyolitic lava flows known as
obsidian flows
, where the chemical composition (high silica content) induces a high viscosity and polymerization degree of the lava. The inhibition of atomic diffusion through this highly viscous and polymerized lava explains the lack of crystal growth. Obsidian is hard and brittle; it therefore fractures with very sharp edges, which had been used in the past in cutting and piercing tools, and are still used as surgical scalpel blades.
Obsidian is the rock formed as a result of cooled magma, which is the parent material. Having a low water content when newly formed typically less than 1% water by weight, 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.
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 usually 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.
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 brown to black color. 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 an iridescent, rainbow-like sheen (
rainbow obsidian
).
Obsidian can be found in locations which have experienced rhyolitic eruptions.
Item Specifics
Total Carat Weight (TCW) :
1000
Natural/Lab-Created :
Natural
Color :
Black
Shape :
Rough
Treatment :
Not Enhanced
Brand :
Unbranded
Country/Region of Manufacture :
China
Carat Range :
Greater than 6.00
Transparency :
Opaque
Country of Origin :
China
Modified Item :
No
Payment
Payment: By Paypal
Shipping cost
Free shipping cost.
We send the goods to USA, Canada, UK, Australia, New Zealand, EU countries and some other European and Asian countries by E-express, a kind of fast postal service by Hong Kong Post. It usually takes about 6 to 10 working days for delivery.
We send the goods to other countries by registered airmail and will take about 8 to 14 working days for delivery.
Return policy
Returns: We accept returns with any reason in 30 days. Buyer will bear the return shipping cost.
Messages
We will answer messages in 24 hours during working days.
[ Policy
: This is the contents of your policies. You can add a banner for this policy as header and add text descriptions here. The text descriptions can be different Font Size, Font Color, Style and even graphics and icons are also accepted. ]
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