Anatase In Quartz | Gemopedia

Anatase is a relatively uncommon gemmy form of titanium dioxide that forms very small unique crystals. The name anatase comes from a Greek word meaning "elongation," referencing its elongated crystal form. Anatase is a polymorph to the more common rutile, as well as brookite. We sometimes see long rutile needles shooting through gemstones, but small anatase crystal inclusions is a much rarer occurrence. Like rutile, anatase usually occurs in honey-yellow, brown to reddish brown, black or deep blue colors.
Colors
Colorless With Orange Brown, Brown, Pale Yellow, Black, Green, Liliac, Gray Inclusions

Anatase In Quartz Classification

Common Name

Anatase In Quartz

Species

Quartz

Variety

Colors

Colorless With Orange Brown, Brown, Pale Yellow, Black, Green, Liliac, Gray Inclusions

Alternate Names

Gemstone Groups

Key Separations

Refractive index, appearance, birefringence, optic character and optic figure. A bull's-eye optic figure is determinative for quartz; may also show Airy's spiral optic figure and Brazil-law twinning under crossed polarizing filters.

Comments

Anatase is a polymorph of rutile and brookite.

Anatase In Quartz Optical Properties

Transparency

Transparent - Translucent

Refractive Index

1.544-1.553
Tolerance:very constant

Birefringence

0.009

Optic Character

Uniaxial

Optic Sign

Positive

Polariscope Reaction

Doubly Refractive (DR)

Fluorescence

SWUV: Inert
LWUV: Inert

CCF Reaction

Pleochroism

None

Dispersion

Strength: weak fire Value: 0.013

Comments

Anatase In Quartz Chemistry & Crystallography

Chemical Name

silicon dioxide (aka silica)

Chemical Formula

SiO2

Synthesis

Crystal System

Trigonal

Classification

Silicate

Nature

Natural

Crystallinity

Crystalline

Comments

Anatase In Quartz Characteristic Physical Properties

Hardness

7

Streak

White

Specific Gravity

2.64-2.69 Typical:2.66

Toughness

Good

Inclusions

Anatase in quartz will have anatase inclusions and may contain liquid, two-phase and three-phase inclusions, negative crystals, minerals, needles, rutile, iron particles.

Luster

Vitreous

Stability

Good

Fracture

Conchoidal

Cleavage

None

Comments

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