Rock Identifier
Petrified Bone (Fossil Bone) (Per mineralization fossil bone (varies by organism, predominantly replacement by SiO2 - Quartz/Chalcedony)) — fossil
fossil

Petrified Bone (Fossil Bone)

Per mineralization fossil bone (varies by organism, predominantly replacement by SiO2 - Quartz/Chalcedony)

Hardness: 6.5-7 on the Mohs scale (due to silica replacement); Color: off-white, beige, tan, gray, to brownish; Luster: dull, earthy, or waxy; Texture: distinct porous, cellular structure characteristic of bone marrow and trabecular tissue visible in cross section.

Hardness
6
Color
off-white, beige, tan, gray, to brownish
Luster
dull, earthy, or waxy
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Physical properties

Hardness: 6.5-7 on the Mohs scale (due to silica replacement); Color: off-white, beige, tan, gray, to brownish; Luster: dull, earthy, or waxy; Texture: distinct porous, cellular structure characteristic of bone marrow and trabecular tissue visible in cross section.

Formation & geological history

Formed via permineralization, a process where groundwater carrying dissolved minerals (most commonly silica or calcium carbonate) fills the microscopic pores within organic bone tissue after burial in sediment, replacing the organic matter over millions of years.

Uses & applications

Valued by collectors and lapidaries. Used for educational display, fossil collections, and occasionally carved or polished into unique cabochons and jewelry pieces.

Geological facts

Fossilized bones often retain the exact cellular microstructure of the living animal's bone. Under magnification, the canals that once held blood vessels and marrow cells are clearly visible, permanently converted to stone.

Field identification & locations

Look for a spongy, porous structure (trabecular bone texture) combined with heavy mineral weight. Licking a real fossil bone often produces a subtle sticking sensation on the tongue due to microscopic porosity. Found in sedimentary rock formations, badlands, and river gravels worldwide.

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