igneous
Obsidian Arrowhead Replica (or similar knapped stone)
Obsidian (volcanic glass) or Chert
Hardness: 5-5.5 (obsidian) or 6.5-7 (chert/flint). Color: Black, dark green, or gray (appears dark/translucent in the image). Luster: Vitreous/glassy. Fracture: Conchoidal, which allows it to be knapped into sharp edges.
- Hardness
- 5-5
- Luster
- Vitreous/glassy
Identified More igneous →
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Physical properties
Hardness: 5-5.5 (obsidian) or 6.5-7 (chert/flint). Color: Black, dark green, or gray (appears dark/translucent in the image). Luster: Vitreous/glassy. Fracture: Conchoidal, which allows it to be knapped into sharp edges.
Formation & geological history
Obsidian forms from the rapid cooling of silica-rich volcanic lava without crystal growth. Chert forms through sedimentary processes. The object is a modern or ancient artifact fashioned through flintknapping.
Uses & applications
Historically used for tools and weapons (arrowheads, spear points, knives). Currently used for jewelry, replicas, and collector's items.
Geological facts
Because obsidian fractures with conchoidal fracture, it can produce edges thinner and sharper than the best surgical steel.
Field identification & locations
Identify by the conchoidal fracture patterns (flake scars) on the surface, typical of knapped tools, and a glassy luster (if obsidian). Found globally where volcanic activity occurred or where chert nodules are present. For collectors, authenticity vs. modern replica is a key distinction.
