• Well tumbled Natural Black Obsidian  Stone (small to medium size pieces)
  • - 0.22 Kg Lot (0.48 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 40 to 88 pieces in each lot
  •  
  •  
  • These stones are from Africa.
  •  
  • The pictures in the listing is 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
  • Nature & Science

    https://stores.ebay.com/Gao-Fu-Collectibles

    Tumbled Black Obsidian Stone 0.5 to 8 g small size pieces 220 gram Lot

    Well tumbled Natural Black Obsidian  Stone (small to medium size pieces)

    - 0.22 Kg Lot (0.48 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 40 to 88 pieces in each lot

     

     

    These stones are from Africa.

     

    The pictures in the listing is 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
    Color Black
    Shape Rough
    Treatment Not Enhanced
    Brand Not branded
    Country of Manufacture China
    Carat Range Greater than 6.00
    Variety/Type Black (Apache Tear)
    Natural/Lab-Created Natural
    Transparency Opaque
    Cut Grade Good
    Modified Item No
    Country of Origin Brazil
    Country/Region of Manufacture China
    Gemstone Type Obsidian
    Gemstone Color Black
    Gemstone Creation Natural
    Gemstone Form Polished
    Gemstone Treatment Not Enhanced
    Gemstone Clarity Grade Eye Clean

    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.

    Messages

    We will answer buyer messages within 24 hours during working days.

    Nature & Science

    https://stores.ebay.com/Gao-Fu-Collectibles

    Shop Category
    Picture
    Custom Item
    Tumbled Black Obsidian Stone 0.5 to 8 g small size pieces 220 gram Lot

    Well tumbled Natural Black Obsidian  Stone (small to medium size pieces)

    - 0.22 Kg Lot (0.48 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 40 to 88 pieces in each lot

     

     

    These stones are from Africa.

     

    The pictures in the listing is 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.


    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.

    Messages

    We will answer buyer messages within 24 hours during working days.


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