Obsidian

Obsidian is a rock which is a type of naturally occurring glass, produced by volcanoes (igneous origin) when a felsic lava cools rapidly and freezes without sufficient time for crystal growth. It is commonly found within the margins of felsic lava flows, where cooling is more rapid. Because of the lack of crystal structure, obsidian blade edges can reach almost molecular thinness, leading to its ancient use as arrowheads and its modern use as surgical scalpel blades.

While a rock like basalt is dark because of ferromagnesian enrichment, obsidian consists mainly of silicon dioxide, usually 70% or more. Obsidian is mineral-like, but not a true mineral because it is not crystalline. Its composition is very similar to that of granite and rhyolite. It is sometimes classified as a Mineraloid because obsidian is metastable at the earth's surface (over time the glass becomes fine-grained mineral crystals). The breakdown of obsidian is accelerated by the presence of water. Tektites were once thought by many to be obsidian produced by lunar volcanic eruptions, though few scientists now agree with this theory.

While pure obsidian is always dark in appearance, the color varies depending on the presence of impurities. Iron and magnesium typically give the obsidian a dark green to brown to black color. In some stones, the inclusion of small, white, radially clustered crystals of Cristobalite in the black glass develop a blotchy or snowflake pattern producing what is known as

Snowflake Obsidian

Obsidian is relatively soft with a typical hardness rating of 5 to 5.5. Obsidian, unlike crystals, has no regular structure and therefore fractures in smooth conchoidal (curved) shapes. The intersections of these fractures can form edges sharper than the finest steel blades. For this reason, obsidian was used by many native cultures to make arrowheads and blades.

The Nevada, Utah and California area, referred to as the Great Basin, is an ideal location to find Obsidian. There are a myriad of colors, patterns and mixes of Obsidians, making them a very desirable collector item.

Snowflake Obsidian is a black obsidian with white spots (spherulites) of radiating needle-shaped cristobalite (high-temperature quartz) crystals.

Below are some pieces from some of our trips to Utah.

Nice Snowflake Obsidian is getting hard to find..... It is from the Black Rock Desert in western Utah where it was geologically deposited approximately 2.5 million years ago (the late Tertiary Period), during volcanic eruptions in the Black Spring area of the Black Rock Desert area in western Utah.

Polished Snowflake Obsidian
Polished Snowflake Obsidian
Polished Snowflake Obsidian
Polished Snowflake Obsidian
Polished Snowflake Obsidian Polished Snowflake Obsidian Polished Snowflake Obsidian Polished Snowflake Obsidian
Item # SO06104381

1 Face Cut and Polished Snowflake Obsidian

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Cut and Polished Face!

Utah Cut and Polished specimen weighs 0.73 lb (332g) and measures 3.1 x 2.3 x 2 inches (79 x 57 x 51mm)

Polished Snowflake Obsidian
Polished Snowflake Obsidian
Polished Snowflake Obsidian
Polished Snowflake Obsidian
Polished Snowflake Obsidian Polished Snowflake Obsidian Polished Snowflake Obsidian Polished Snowflake Obsidian
Item # SO06105381

1 Face Cut and Polished Snowflake Obsidian

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Cut and Polished Face!

Utah Cut and Polished specimen weighs 0.76 lb (346g) and measures 4.3 x 2 x 1.9 inches (109 x 50 x 48mm)

Rough Snowflake Obsidian
Rough Snowflake Obsidian
DSCN4359 (1)
Rough Snowflake Obsidian
Rough Snowflake Obsidian Rough Snowflake Obsidian DSCN4359 (1) Rough Snowflake Obsidian
Item # 7OBS0913U002

4.26 lb Rough Snowflake Obsidian

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Utah specimen weighs 68.2 oz or 4.26 lb (1933g) and measures 5.8 x 4.2 x 3.8 inches (14.9 x 10.8 x 9.8cm)

Photographed dry in outdoor sunlight/shade with a Nikon CoolPix L1

Rough Snowflake Obsidian
Rough Snowflake Obsidian
Rough Snowflake Obsidian
Rough Snowflake Obsidian
Rough Snowflake Obsidian Rough Snowflake Obsidian Rough Snowflake Obsidian Rough Snowflake Obsidian
Item # 9OBS0913U004

2.01 lb Rough Snowflake Obsidian

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Utah specimen weighs 32.3 oz or 2.01 lb (916g) and measures 4.5 x 3.2 x 2.9 inches (11.5 x 8.2 x 7.3cm)

Photographed dry in outdoor sunlight/shade with a Nikon CoolPix L1

Snowflake
Snowflake
Snowflake
Snowflake Snowflake Snowflake
Item # 34SOBPN08151002

Polished Free Form Snowflake "Firecracker" Obsidian Nodule

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Very beautiful polished nodule specimen of Firecracker/Fireworks Obsidian

Photographed dry in outdoor sunlight/shade with a Nikon CoolPix L1. Fireworks Obsidian is from Mexico. It has a good polish and cuts easily but is not suitable for knapping. As with all rocks from nature, there are fracture lines either visible or invisible. Light pink and grey are the colors of these distinct exploding bursts on display against the backdrop of midnight black obsidian. Some portions of Fireworks Obsidian may be porous. It is not as smooth a surface as normal snowflake obsidian

weighs 10.5 oz or 0.65 lb (297g) and measures 3.2 x 2.6 x 1.7 inches (8.1 x 6.6 x 4.4 cm)