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 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