How to identify Fossilized Bone

To correctly identify Fossilized Bone (Fossilized 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

   Highly variable, often shades of brown, tan, gray, black, or reddish, depending on the mineralizing agents (e.g., iron oxides for red/brown, manganese for black, silica for lighter colors).

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Dull to earthy, sometimes waxy or vitreous if heavily silicified.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Often exhibits a porous, spongy, or fibrous texture characteristic of bone. The surface may be smooth, rough, or show remnants of vascular canals or bone lamellae. Can feel dense and heavy due to mineralization.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Does not exhibit a distinct crystal form in the macroscopic sense, as it is a permineralized or replaced organic structure. The mineral components (e.g., apatite, quartz) may be microcrystalline.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   None, as it is an aggregate of mineralized organic material. It will fracture irregularly.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Found in sedimentary rock formations, particularly those formed in environments conducive to rapid burial and mineralization, such as fluvial (river), lacustrine (lake), marine, and sometimes volcanic ash deposits. Common in sandstones, shales, limestones, and conglomerates.

Key Facts

Hardness

Variable, typically 3-7 on the Mohs scale, depending on the degree and type of mineralization. Original bone apatite is around 5, but silicification can increase it to 7.

Specific Gravity

Variable, typically 2.0-3.0, depending on the degree and type of mineralization. Original bone is around 1.9-2.1, but mineral replacement increases density.

Crystal System

Not applicable to the overall fossilized bone structure. The mineral components (e.g., apatite) are hexagonal; quartz is trigonal.

Color

Brown, gray, black, tan, reddish, or off-white.

Luster

Dull, earthy, sometimes waxy or vitreous.

Transparency

Opaque.

Fracture

Irregular to conchoidal (if heavily silicified).

Cleavage

None.

Composition

Primarily calcium phosphate (hydroxyapatite, Ca5(PO4)3(OH)) replaced or permineralized by various minerals such as silica (SiO2), calcite (CaCO3), iron oxides (e.g., hematite, Fe2O3), or pyrite (FeS2).

Physical characteristics

• Crystal Habit: Not applicable; it is a pseudomorph after organic material. Mineral components are microcrystalline.
• Cleavage Type: None.
• Fracture Type: Irregular to conchoidal.
• Tenacity: Brittle.
• Luster Type: Dull, earthy, waxy, or vitreous.

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