How to identify Fossilized Bone Fragment

To correctly identify Fossilized Bone Fragment (Bone (fossilized)), 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, ranging from white, gray, black, brown, tan, red, yellow, or even blue/green, depending on the mineral infilling (e.g., iron oxides for reds/yellows, manganese for blacks, copper for blues/greens, silica for whites/grays).

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

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

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Often porous, spongy, or fibrous, reflecting the original bone structure. Can be smooth if highly abraded or polished. Microscopic examination often reveals Haversian canals or other bone microstructures.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Amorphous to microcrystalline, as the original bone structure is preserved or replaced by fine-grained minerals. Does not typically exhibit macroscopic crystal forms.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   None, as it is not a true mineral with a defined crystal lattice. Fracture is typically irregular or conchoidal if highly silicified.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Found in sedimentary rocks, particularly sandstones, siltstones, mudstones, limestones, and conglomerates. Common in fluvial (river), lacustrine (lake), marine, and terrestrial depositional environments where rapid burial and mineral-rich groundwater were present. Often associated with fossil-rich beds, bone beds, and ancient floodplains or deltas.

Key Facts

Hardness

Variable, typically 3-7 on the Mohs scale, depending on the degree and type of mineralization (e.g., 3 for calcite-replaced, 7 for quartz-replaced). Original bone (hydroxyapatite) is around 5.

Specific Gravity

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

Crystal System

Amorphous to microcrystalline (no defined crystal system for the overall fossil, though infilling minerals may have their own crystal systems).

Color

Highly variable, influenced by infilling minerals and surrounding sediments.

Luster

Dull to earthy, sometimes waxy or vitreous.

Transparency

Opaque.

Fracture

Irregular to conchoidal (if highly silicified).

Cleavage

None.

Composition

Primarily calcium phosphate (hydroxyapatite) replaced or permineralized by various minerals such as silica (SiO2), calcite (CaCO3), iron oxides (e.g., Fe2O3, FeO(OH)), pyrite (FeS2), or other phosphates. The original organic components are typically absent.

Physical characteristics

• Crystal Habit: Massive, amorphous, or preserving the original cellular and structural morphology of bone.
• Cleavage Type: Not applicable (no cleavage).
• Fracture Type: Irregular, splintery, or conchoidal (depending on mineralization).
• Tenacity: Brittle.
• Luster Type: Dull, earthy, waxy, or vitreous.

Explore Fossilized Bone Fragment