Amethyst | Gemopedia

Whether in faceted stones, crystal specimens, polished pebbles or beads, amethyst has enjoyed popularity in nearly every culture throughout its ancient history. Before the lucrative deposits of Africa and South America were discovered, amethyst was as treasured as ruby and emerald. February's traditional birthstone, striking purple amethyst is the most popular gemstone of the quartz group.
Alternate
Names
Spirit Quartz If It Has Secondary Pale Amethyst Growth Coverage, Rose Of France If Pale Lilac
Colors
Purple Through Violetish Purple

Amethyst Classification

Common Name

Amethyst

Species

Quartz

Variety

Amethyst

Colors

Purple Through Violetish Purple

Alternate Names

Spirit Quartz If It Has Secondary Pale Amethyst Growth Coverage, Rose Of France If Pale Lilac

Gemstone Groups

Key Separations

Refractive index, birefringence, optic character and optic figure. A bull's-eye optic figure is determinative for quartz. Might also show Airy's spiral. The presence of Brazil-law twinning is a means of separating amethyst from scapolite.

Comments

Amethyst is commonly found in geodes. 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.

Amethyst 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 to weak blue
LWUV: Inert

CCF Reaction

Pleochroism

Dichroic, weak to moderate purple and reddish purple

Dispersion

Strength: weak fire Value: 0.013

Comments

Amethyst Chemistry & Crystallography

Chemical Name

silicon dioxide (aka silica)

Chemical Formula

SiO2

Synthesis

Crystal System

Trigonal

Classification

Silicate

Nature

Natural

Crystallinity

Crystalline

Comments

Amethyst Characteristic Physical Properties

Hardness

7

Streak

White

Specific Gravity

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

Toughness

Good

Inclusions

Amethyst 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

History
Amethyst's existence has been known since ancient times. Ancient Greeks, Romans, and Egyptians used amethysts in jewelry and household goods like bowls and cups. Even in ancient Mesopotamia, amethysts were engraved with royal and religious insignia and used as tools to imprint clay tablets. Amethyst has been symbolic of purity and royalty used in jewelry for hundreds of years. Amethyst has long played an important role in religion, as the stone in Christian bishops' rings and in rosaries.
Origin
Amethyst gets its name from the Greek words amethystos or amethustos, meaning "not drunken," because of the ancient belief that drinking wine from an amethyst cup--or, unfortunately, grinding amethyst into powder and adding it to wine--would help maintain sobriety.
Learn More
Amethyst was considered a symbol of a bishop's fine spirituality in the early Christian church. Amethyst rings soon became a standard part of a bishop's regalia, and for this reason, high-quality, fine-color amethyst is sometimes referred to as "bishop's grade" in the gemstone industry.
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