Rock Identifier
Mother of Pearl (Nacre) / Shell Fragment (Biogenic Calcium Carbonate (Aragonite and Conchiolin)) — fossil
fossil

Mother of Pearl (Nacre) / Shell Fragment

Biogenic Calcium Carbonate (Aragonite and Conchiolin)

AI-generated identification · may be incorrect

Hardness: 3.5 to 4 on the Mohs scale, Color: Iridescent white, pearlescent, cream, Luster: Pearly to vitreous, Crystal Structure: Orthorhombic (aragonite platelets), Cleavage: None, Specific Gravity: 2.65 to 2.76

Hardness
3
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Physical properties

Hardness: 3.5 to 4 on the Mohs scale, Color: Iridescent white, pearlescent, cream, Luster: Pearly to vitreous, Crystal Structure: Orthorhombic (aragonite platelets), Cleavage: None, Specific Gravity: 2.65 to 2.76

Formation & geological history

Formed organically as an internal shell layer by marine mollusks (such as pearl oysters, freshwater mussels, and abalones) over periods of months to years, often found in coastal marine or riverine sedimentary environments.

Uses & applications

Used in jewelry, inlay work, decorative buttons, knife handles, and as a holistic crystal healing specimen.

Geological facts

Nacre is a composite material made of microscopic aragonite tablets bound together by an organic matrix (conchiolin), making it extremely tough and resilient to fracture compared to pure crystalline aragonite.

Field identification & locations

Easily identified by its characteristic pearlescent iridescence, lamellar growth lines, and organic texture. Found globally along beaches, riverbanks, and fossiliferous sedimentary deposits.

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