How to identify Dinosaur Bone Agate

To correctly identify Dinosaur Bone Agate (Silicified Dinosaur Bone), check each of these features in order. Many rocks and minerals look alike, so cross-reference multiple properties before deciding.

Step-by-step identification

1. 1

   Color

   Overall color and any zoning or banding

   Extremely variable, ranging from black, gray, white, brown, tan, yellow, orange, red, pink, purple, blue, and green. Often multi-colored with distinct patterns.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Vitreous (glassy) to waxy.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Smooth when polished, but can feel slightly granular or porous on unpolished surfaces. The most distinguishing feature is the visible cellular structure of the original bone.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Microcrystalline, typically chalcedony, filling and replacing the bone structure. No macroscopic crystal forms are present.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   None, as it is a microcrystalline aggregate.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Found in sedimentary rock formations where dinosaur remains were rapidly buried and subsequently exposed to silica-rich groundwater. Common in fluvial (river) and lacustrine (lake) deposits.

Key Facts

Hardness

6.5-7 on the Mohs scale (due to the chalcedony/quartz replacement).

Specific Gravity

2.58-2.64 (similar to quartz).

Crystal System

Trigonal (for the constituent quartz/chalcedony, but the overall form is pseudomorphic after bone).

Color

Wide range, including black, gray, white, brown, tan, yellow, orange, red, pink, purple, blue, green. Often variegated.

Luster

Vitreous to waxy.

Transparency

Opaque to translucent.

Fracture

Conchoidal to uneven.

Cleavage

None.

Composition

Primarily silicon dioxide (SiO2) in the form of chalcedony, with trace impurities causing coloration. Original bone material (calcium phosphate) is largely replaced.

Physical characteristics

• Crystal Habit: Pseudomorphic after bone; microcrystalline aggregate (chalcedony).
• Cleavage Type: None.
• Fracture Type: Conchoidal to uneven.
• Tenacity: Brittle.
• Luster Type: Vitreous to waxy.

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