Obsidian

SiO2

This specimen is a dark, glassy volcanic rock, specifically snowflake obsidian, characterized by its black base color adorned with distinct white to gray, radial patterns resembling snowflakes.

Obsidian Physical Properties

Mohs Hardness

Crystal System

amorphous

Luster

vitreous

Streak Color

white

Cleavage

none

Fracture

conchoidal

Specific Gravity

2.35

Colors

black, dark brown, dark green, gray, white

Transparency

translucent

Type Locality

Volcanic regions worldwide (e.g., USA, Mexico, Iceland, Italy)

Mineral Group

Volcanic glass (mineraloid)

Uses

jewelry, tools, surgical instruments, decorative objects, collector

Associated Minerals

quartz, feldspar, cristobalite

Rarity

common

Geological Context

Obsidian forms from the rapid cooling of felsic lava, typically rhyolitic in composition, preventing the formation of a crystalline structure. It is found in areas of recent volcanic activity.

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Related Specimens

Variscite

Garnet

Rutilated Quartz

Hemimorphite

Diaspore