amorphous simulant ivory simulant

Bone (Ivory Simulant)

Ca5(PO4)3(OH) (hydroxyapatite; same general composition as ivory dentine) in collagen matrix; technically microcrystalline hydroxyapatite but gemologically treated as amorphous/aggregate biomineral

Quick Facts

Hardness

2.0

Specific Gravity

1.7

Refractive Index

1.54

Optical Character

AGG

Crystal Structure

CDL Notation

 #! Species: Bone (biomineral; ivory simulant)
#! System: Amorphous (composite biomineral: apatite + collagen)
#! Habit: Massive; carved and polished
amorphous[waxy]:{massive}

Crystal System amorphous

Point Group none

Crystal Forms (1)

{massive}

Physical Properties

Crystal Systemamorphous

Hardness (Mohs)2.0

Specific Gravity1.7

CleavageNone

FractureConchoidal to splintery

LustreWaxy to dull

Optical Properties

Refractive Index1.54

Optical CharacterAGG

FluorescenceWhite-blue (LWUV; similar to ivory; not diagnostic for separation)

Origin & Identification

Originsimulant

Diagnostic FeaturesHaversian canals (osteon/concentric ring microstructure around central channel; visible at 10x-40x) PRESENT in bone; ABSENT in ivory; absence of Schreger lines in bone (ivory has characteristic cross-hatch arcs at 100-130 degrees in cross-section); SG 1.70-2.00 (slightly lower than ivory 1.85-1.95)

Colours

White to cream-white; yellowing with age from collagen degradation; may be bleached

Common Inclusions

Haversian canals (osteon structure; parallel pore-like dots in cross-section; diagnostic of bone; ABSENT in ivory); absent Schreger lines (ivory has them; bone does not)

Notes

Skeletal bone from domestic animals (cattle, pigs, horses); carved, bleached and polished as ivory simulant. Crystal system set to amorphous (same convention as other organic/ biomineral entries). Note: technically hydroxyapatite is hexagonal, but bone as a whole is a composite biomineral (amorphous collagen + microcrystalline apatite) — gemologically treated as amorphous aggregate. Primary separation from ivory confirmed by Jha et al. 2017, Journal of Institute of Science and Technology 22(1):17745 (DOI 10.3126/jist.v22i1.17745) [VERIFIED]: "The presence of Schreger line is the identifying feature of an elephant tusk" — Schreger lines ABSENT in bone; Haversian canals ABSENT in ivory. These are the definitive microscopical diagnostics. SG 1.70-2.00 is lower than ivory (1.85-1.95; slight overlap). Hot-point: both give "burnt bone" smell (not diagnostic for separating bone from ivory; but distinguishes from plastic and vegetable ivory). CITES context: unlike elephant ivory, bone from domestic animals has no trade restriction — but fraudulent substitution is an issue.

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CDL Notation

 #! Species: Bone (biomineral; ivory simulant)
#! System: Amorphous (composite biomineral: apatite + collagen)
#! Habit: Massive; carved and polished
amorphous[waxy]:{massive}