Obsidian

saf-ahyuh r

Obsidian has been used since the Stone Age for tools, weapons and as an ornamental material. It has also been used in modern times as scalpel blade. Obsidian is formed by the rapid cooling of viscous lava due to volcanic explosions. It consists of the same minerals as granite but cools so quickly that they do not have time to crystallize. Obsidian has a glassy luster and is usually black or a very dark green, but it can also be found in an almost colorless form.

Obsidian Polished
Obsidian Classification
Common Name Obsidian
Species Glass
Obsidian Optical Properties
Transparency Transparent - Opaque
Dispersion Strength: Weak Fire Value: 0.010
Refractive Index 1.490
Tolerance:(+0.020/-0.010)
Optic Character NA
Optic Sign NA
Polariscope Reaction Singly Refractive (SR) With ADR
Fluorescence SWUV: Inert
LWUV: Inert
Pleochroism None
Obsidian Characteristic Physical Properties
Hardness 5-5.5
Streak White
Specific Gravity 2.330-2.600 Typical:2.400
Toughness Varies
Inclusions Obsidian often has gas bubbles, cristobalite inclusions and stubby needle like inclusions. Banded obsidian: curved or sinuous bands.
Luster Vitreous, Greasy
Fracture Conchoidal
Cleavage None
Obsidian Chemistry & Crystallography
Chemical Name silica
Chemical Formula SiO2(MgO,Fe3O4)
Crystal System NA
Chemistry Classification Mineraloid

Obsidian Colors

  • Brown Obsidian Brown
  • Yellow Obsidian Yellow
  • Red Obsidian Red
  • Multi-color Obsidian Multi-color
  • Green Obsidian Green
  • Gray Obsidian Gray
  • Black Obsidian Black

Alternate Names

Banded Obsidian, Onyx Obsidian, Sheen Obsidian, Snowflake Obsidian, Rainbow Obsidian, Apache Tears, Mahogany Obsidian

Countries of Origin

Argentina; United States of America (the); Czechia; Uruguay; Japan; Iceland; Unknown; China; Italy; Mexico; South Africa; Australia; Peru; Indonesia

History

Because of its conchoidal fracture obsidian is an excellent material for spearheads, knives and arrowheads. In 1995 an obsidian bracelet that dated from 7500 BC was found at an archeological site in Aşıklı Höyük, Turkey. This bracelet shows superior craftmanship not known before the discovery of this artifact.

Care

Avoid heat, chemicals, and ultrasonic cleaners.

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Species/Variety

Spiderweb Obsidian

Spiderweb obsidian comes from Guadalajara, Mexico. The material is dark blue and is named for the light blue veins that look like spider webs running throughout the stones.

Spiderweb Obsidian Obsidian
Spiderweb Obsidian Classification
Common Name Spiderweb Obsidian
Spiderweb Obsidian Characteristic Physical properties
Specific Gravity 2.33
Toughness Fair
Inclusions Gas bubbles, blue veining

Velvet Obsidian

Velvet obsidian is a rare form of obsidian that comes from Mexico that resembles crushed velvet. It is also known as peacock obsidian when the colors in the stone mimic the appearance of a peacock's tail.

Velvet Obsidian Obsidian
Velvet Obsidian Classification
Common Name Velvet Obsidian
Velvet Obsidian Characteristic Physical properties
Specific Gravity 2.33
Toughness Fair
Inclusions Gas bubbles
Stability Fair

Mahogany Obsidian

Mahogany obsidian can be identified by its red and black bands. The color is thought to come from hematite or iron impurities. The material is similar in appearance to the mahogany variety of wood. Most mahogany obsidian comes from Mexico.

Mahogany Obsidian Obsidian
Mahogany Obsidian Classification
Common Name Mahogany Obsidian
Mahogany Obsidian Characteristic Physical properties
Specific Gravity 2.33
Toughness Fair
Inclusions Gas bubbles, banding
Stability Fair

Snowflake Obsidian or Flowering Obsidian

Snowflake or flowering obsidian contains white patches of cristobalite inclusions on a black background. Most material is found in Utah or Wyoming in Utah.

Snowflake Obsidian or Flowering Obsidian Obsidian
Snowflake Obsidian or Flowering Obsidian Classification
Common Name Snowflake Obsidian or Flowering Obsidian
Snowflake Obsidian or Flowering Obsidian Characteristic Physical properties
Specific Gravity 2.33
Toughness Fair
Inclusions Gas bubbles, cristobalite
Stability Fair

Sheen Obsidian

Sheen obsidian can have a silvery or golden looking sheen caused by linear trails gas bubbles throughout the stone.

Sheen Obsidian Obsidian
Sheen Obsidian Classification
Common Name Sheen Obsidian
Sheen Obsidian Characteristic Physical properties
Specific Gravity 2.33
Toughness Fair
Inclusions Long trails of gas bubbles
Stability Fair

Macusanite Obsidian

Macusanite obsidian is a pale yellow to greenish obsidian from Macusani volcanic field Carabaya Province of Peru.

Macusanite Obsidian Obsidian
Macusanite Obsidian Classification
Common Name Macusanite Obsidian
Macusanite Obsidian Characteristic Physical properties
Specific Gravity 2.33
Toughness Fair
Inclusions Gas bubbles
Stability Fair

Onyx Obsidian

Onyx obsidian is obsidian with straight, parallel bands.

Onyx Obsidian Obsidian
Onyx Obsidian Classification
Common Name Onyx Obsidian
Onyx Obsidian Characteristic Physical properties
Specific Gravity 2.33
Toughness Fair
Inclusions Gas bubbles
Stability Fair

Rainbow Obsidian

Rainbow obsidian comes from Mexico and it is named for the rainbow colors it displays. The rainbow appearance comes from thin-film interference due to inclusions of oriented nanorods of hedenberite.

Rainbow Obsidian Obsidian
Rainbow Obsidian Classification
Common Name Rainbow Obsidian
Rainbow Obsidian Characteristic Physical properties
Specific Gravity 2.33
Toughness Fair
Inclusions Gas bubbles
Stability Fair

Fire Obsidian

Fire obsidian is a variety of iridescent obsidian, that comes from Southeast Oregon, that displays vibrant colors and patterns. The color is caused by thin-film interference due to thin layers of concentrated nano-crystals of magnetite.

Fire Obsidian Obsidian
Fire Obsidian Classification
Common Name Fire Obsidian
Fire Obsidian Characteristic Physical properties
Specific Gravity 2.33
Toughness Fair
Inclusions Gas bubbles
Stability Fair

Apache Tears

Apache tears are small, rounded irregularly shaped obsidian nodules found in the American Southwest typically in Arizona and New Mexico. They are dark gray to brownish or greenish black. Apache tears are said to be the preserved tears of the Apache women who lost their beloved warriors in battle.

Apache Tears Obsidian
Apache Tears Classification
Common Name Apache Tears
Apache Tears Characteristic Physical properties
Specific Gravity 2.33
Toughness Fair
Inclusions Gas bubbles
Stability Fair
Tim Matthews

Author

Tim Matthews

Tim Matthews is President and Chief Executive Officer of Jewelry Television® (JTV), as well as a member of the company's Board of Directors. He oversees and leads all aspects of the company's powerful omni-digital retail platform that uniquely specializes in fine jewelry and gemstones. His passion for business and gemstones has led him to become a recognized expert in the field of gemology. He is a life member of the Gemmological Association of Great Britain (Gem-A) and has earned Gem-A's highest degrees, the Gemmology (FGA) and Diamond (DGA) diplomas. He is also a Graduate Gemologist (GG) of the Gemological Institute of America (GIA) and has also completed GIA's Graduate Diplomas in Diamonds, Colored Stones and Pearls. Under his leadership, JTV has become the leader in the sourcing and selling of color gemstones and jewelry.

This page was created on June 27, 2014.

This page was last edited on October 24, 2019.