Ametrine | Gemopedia

Ametrine is a bi-color quartz variety that, as its name suggests, is a unique combination of amethyst and citrine within a single crystal. How the gem forms is still a bit of a mystery, but the differences in color are believed to be the result of the presence of iron in different states of oxidation from natural heating. Combining the golden sunburst of citrine with the violet sunset of amethyst, this naturally colored gem is commercially mined at a single source: the remote Anah mine in Bolivia and is shrouded in fascinating local legends and lore.
Alternate
Names
Trystine, Bolivianite, Amethyst-Citrine, Citrine-Amethyst, Golden Amethyst
Colors
Bicolored Combination Of Purple, Yellow

Ametrine Classification

Common Name

Ametrine

Species

Quartz

Variety

Ametrine

Colors

Bicolored Combination Of Purple, Yellow

Alternate Names

Trystine, Bolivianite, Amethyst-Citrine, Citrine-Amethyst, Golden Amethyst

Gemstone Groups

Key Separations

Ametrine's appearance is distinctive and otherwise the key quartz indicators will be present (refractive index, birefringence, optic character and optic figure). A bull's-eye optic figure is determinative for quartz. Might also show Airy's spiral.

Comments

Stones might be piezoelectric: able to generate electricity produced by mechanical pressure,Pyroelectricity: development of opposite charges at the ends of the axis due to change in temperature and triboluminescent: luminescence produced by friction.

Ametrine Optical Properties

Transparency

Transparent - Translucent

Refractive Index

1.544-1.553
Tolerance:very constant

Birefringence

0.009-0.009

Optic Character

Uniaxial

Optic Sign

Positive

Polariscope Reaction

Doubly Refractive (DR)

Fluorescence

SWUV: Inert
LWUV: Inert

CCF Reaction

Pleochroism

Dichroic, weak yellow-orange and purple

Dispersion

Strength: weak fire Value: 0.013

Comments

Ametrine Chemistry & Crystallography

Chemical Name

silicon dioxide (aka silica)

Chemical Formula

SiO2

Synthesis

Crystal System

Trigonal

Classification

Silicate

Nature

Natural

Crystallinity

Crystalline

Comments

Ametrine Characteristic Physical Properties

Hardness

7

Streak

White

Specific Gravity

2.64-2.69 Range:0.03/-0.02 Typical:2.66

Toughness

Good

Inclusions

Ametrine is a type II clarity stone. Color zoning in stones is often present in the form of "soap scum", "tiger stripes" or "zebra stripes", crystals, negative crystals, liquid inclusions, two-phase inclusions, partially-healed fractures, hematite needles.

Luster

Vitreous

Stability

Good

Fracture

Conchoidal

Cleavage

None

Comments

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