FLINT, a variety of chalcedony known for making blades

VARIETY INFORMATION:

• VARIETY OF: Crypto-crystalline Quartz , SiO2
• USES: Gemstone and ornamental stone.
• COLOR: usually black, dark gray, or brown, but may be other colors
• HARDNESS: 7
• CLEAVAGE: none
• CRYSTAL SYSTEM: none visible (actual crystals are microscopic)
• For natural Flint mineral specimens see our For Sale or Sold lists

Flint is a variety of chalcedony (cryptocrystalline quartz) known for its ease of forming blades (including spear tips and arrowheads). It is a fine-grained quartz whose crystals are too small to see.

Flint may be black, gray, brown, and occasionally dark green or even white. It is found in nodules, often with a white coating. The microscopic crystals of flint have a fibrous habit, which results in a notable behavior when chipped: the pieces are sharp, thin splinters called blades (if large) or flakes (if small).

Repeated chipping (knapping) a piece of flint can result in a carefully shaped arrowhead with an extremely sharp edge.

Another use of flint is in a "flintlock", a device where a small piece of flint is struck against a steel plate, releasing sparks to ignite gunpowder or start a fire.

Flint is only one of several chalcedony (cryptocrystalline quartz) varieties. The primary varieties are as follows:

• Agate is a banded variety (sometimes with translucent bands)
• Bloodstone is green with red speckles
• Carnelian is yellow to orange
• Chrysoprase is green
• Flint is generally black with a fibrous microscopic structure
• Jasper is any colorful agate
• Onyx is black, white, or alternating black and white
• Sard is yellow to brown
• Sardonyx is banded, alternating sard and (usually white) onyx

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