amorphous Simulant jet simulant

Vulcanite (Jet Simulant)

Formula Sulfur-vulcanised natural rubber (polyisoprene cross-linked by S-S bonds; ~30-35% sulfur content in hard vulcanite/ebonite)

Crystal Structure

CDL Notation

 #! Species: Vulcanite (vulcanised rubber; jet simulant)
#! System: Amorphous (polymer)
#! Habit: Moulded masses; black with brown oxidation tinge
amorphous[resinous]:{massive}

Crystal System amorphous

Point Group none

Crystal Forms (1)

{massive}

Quick Facts

Hardness

2.5

Specific Gravity

1.1

Refractive Index

1.66

Optical Character

Isotropic

Physical Properties

Crystal System: amorphous
Hardness (Mohs): 2.5
Specific Gravity: 1.1
Cleavage: None
Fracture: Uneven
Lustre: Brilliant to waxy

Optical Properties

Refractive Index: 1.66
Birefringence: 0
Optical Character: Isotropic
Fluorescence: Inert

Origin & Identification

Origin: Simulant
Manufacturer: Multiple 19th-early 20th century manufacturers (Victorian era jewellery production)
First Produced: 1843
Diagnostic Features: Sulfur/rubber smell on hot-point test (definitive vs jet coal smell); brown surface tinge from oxidised sulfur (absent in jet and French jet); SG 1.10-1.20 (lower than jet 1.30-1.35); warm to touch (low thermal conductivity); mould seams visible on Victorian pieces; may brown with UV exposure

Characteristics

Colours

Black (body colour); brown surface tinge developing with age from sulfur oxidation

Common Inclusions

Mould seams visible at edges (Victorian moulded pieces)

Notes

Vulcanisation process (rubber + sulfur heated under pressure) invented by Goodyear/Hancock 1843; jewellery use 1850s-1920s for Victorian mourning jewellery as jet simulant. Diagnostic: sulfurous/rubber smell on hot-point test (acrid; vs jet which gives aromatic coal smell). Brown surface tinge from sulfur oxidation in old pieces (true jet stays black). SG 1.10-1.20 lower than jet 1.30-1.35. RI ~1.66 (similar to jet; not diagnostic for separation). Read 7th ed. pp.329-330 (DOI 10.4324/9780080507224) [PARTIALLY_SUPPORTED]. VERIFIED.md status [UNVERIFIED] for dedicated peer-reviewed paper — classified per S-013. Included as curriculum-standard simulant (gemmological teaching content). Key three-way separation: jet = aromatic coal smell + SG 1.30-1.35; vulcanite = sulfur/ rubber smell + SG 1.10-1.20 + brown tinge; French jet = no smell + cold feel + SG 2.40-3.50.