Jet | Gemopedia

Jet is generally classified as a lignite coal and has a high carbon content and a layered structure. It is typically black to dark brown and can sometimes contain tiny inclusions of pyrite. Jet has been carved for ornamental purposes since prehistoric times.
Alternate
Names
Whitby Jet
Colors
Very Dark Brown To Black

Jet Classification

Common Name

Jet

Species

Jet

Variety

Colors

Very Dark Brown To Black

Alternate Names

Whitby Jet

Gemstone Groups

Key Separations

RI and SG(low heft), hot point coal like smell. Stones have very low heft and will sometimes have a spot RI of 1.680.

Comments

Misnomer: black amber. Warm to touch. Becomes electrically charged when rubbed with wool. Jet will break rather than than curl when shaved.

Jet Optical Properties

Transparency

Semitranslucent - Opaque

Refractive Index

1.66
Tolerance:(+0.020/-0.020)

Birefringence

Optic Character

NA

Optic Sign

Polariscope Reaction

Singly Refractive (SR)

Fluorescence

SWUV: inert
LWUV: inert

CCF Reaction

Pleochroism

None

Dispersion

Strength: none

Comments

Jet Chemistry & Crystallography

Chemical Name

hydrated hydro carbon

Chemical Formula

C,H,O-2H2O

Synthesis

Crystal System

NA

Classification

Organic

Nature

Natural

Crystallinity

Non-Crystalline

Comments

Jet Characteristic Physical Properties

Hardness

2.5-4

Streak

Black-Brown

Specific Gravity

1.19-1.34 Typical:1.32

Toughness

Poor

Inclusions

In some Jet specimens the original wood structure can be seen.

Luster

Vitreous

Stability

Fracture

Conchoidal

Cleavage

None

Comments

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