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Quartz

Rock Crystal

Colorless transparent quartz

Colorless
Optical properties

Optical characteristics

Ref. index
1.544 – 1.553
Birefringence
0.009
Luster
Vitreous
Pleochroism
Weak to none Usually weak to none.
Fluorescence
Usually inert to weak.
Origins

Source localities

Brazil Brazil: Minas Gerais / Paraíba / Bahia
Major

Major source for beryl, tourmaline, quartz, topaz, chrysoberyl and rare minerals.

28.5% est. supply
Madagascar Madagascar: Ilakaka / Andranondambo region
Major

Modern major source for sapphire, garnet, beryl, quartz, tourmaline and many collector gems.

33.7% est. supply
United States USA: major gem fields
Notable

Diverse sources for turquoise, tourmaline, opal, sapphire, topaz, red beryl and rare minerals.

18.9% est. supply
Alpine region Alps: alpine fissure localities
Notable

Known for rock crystal and alpine mineral specimens.

18.9% est. supply
Treatments

Enhancement & treatment

Surface Enhancement Surface Coating Coatings create color or optical effects on the surface only. They can be damaged… Composite Appearance Quench Crackling and Dyeing Thermal shock creates cracks that are then dyed to imitate more valuable or unusual… Heat Heat Treatment, Quartz Heating is common in commercial citrine and other quartz colors. It changes color centers… Color Enhancement Irradiation, Quartz Irradiation modifies quartz color centers. The result may imitate natural smoky quartz, citrine, or…
Inclusions

Inclusions & features

Zoning Color Zoning Under 10x loupe in immersion: bands or patches of deeper or lighter color arranged… Crystals Crystal Inclusions Under 10x loupe: solid, well-formed mineral crystals trapped inside the host gem. They may… Fractures Feathers and Fractures Under 10x loupe: irregular internal surfaces that catch light and appear bright, wing-like, or… Fractures Fingerprint Inclusions Under 10x loupe: curved or wavy lines of tiny dots forming patterns that look… Crystals Negative Crystals Under 10x loupe: an empty cavity that has the geometric shape of the host… Clouds Pinpoint Clouds Under 10x loupe: concentrations of extremely tiny bright dots that individually are too small… Multiphase Two-Phase Inclusions Under 10x loupe: a transparent irregular cavity containing both a liquid phase and a…
Identification

Instruments used

10x Loupe Your most-used instrument, start every examination here Polariscope Determines single vs. double refraction, quick and conclusive Refractometer Measures refractive index, the backbone of gem identification UV Lamp, Long Wave and Short Wave Fluorescence exposes treatments, synthetics, and origin