sedimentary
Belemnite Fossil
Belemnitida (extinct order of Cephalopods)
Hardness: 3-4 (Calcite); Color: Tan, brown, or gray; Luster: Vitreous to dull; Structure: Tapered bullet shape with concentric growth rings in cross-section; Cleavage: None (fractures radially).
- Hardness
- 3-4 (Calcite)
- Color
- Tan, brown, or gray
- Luster
- Vitreous to dull
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Physical properties
Hardness: 3-4 (Calcite); Color: Tan, brown, or gray; Luster: Vitreous to dull; Structure: Tapered bullet shape with concentric growth rings in cross-section; Cleavage: None (fractures radially).
Formation & geological history
Formed from the fossilized internal shell (rostrum) of a squid-like mollusk. These organisms lived during the Jurassic and Cretaceous periods (approximately 201 to 66 million years ago) in marine environments.
Uses & applications
Primarily used as educational specimens, collectibles, and occasionally in jewelry as pendants. Historically used in folk medicine (as 'thunderstones').
Geological facts
Ancient folklore referred to these as 'thunderbolts' cast from the sky during storms. They are related to modern squid and octopuses but had a hard internal skeleton to help them swim.
Field identification & locations
Identify by the 'bullet' shape and characteristic point. Often found in chalk, limestone, or coastal clay deposits. Common locations include the Jurassic Coast of the UK and various Cretaceous formations in the USA and Russia.
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