Amethyst
Quartz var. Amethyst · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal; habitually occurs as hexagonal prisms terminated by rhombohedra. In this specimen, it is a massive crystalline fragment.
Mineral Group
Silicates (Tectosilicate)
Chemical Formula
SiO2 with Fe4+ (iron) impurities and natural radiation
Formation Process
Hydrothermal; typically formed in volcanic cavities (geodes) or hydrothermal veins at low to moderate temperatures from silica-rich fluids.
About This Crystal
A translucent to transparent specimen featuring a vibrant violet color with horizontal color zoning. It exhibits a vitreous luster and a rough, crystalline surface on its fractured faces.
Physical Characteristics
Color: Pale to deep purple; Streak: White; Cleavage: None; Fracture: Conchoidal to uneven; Specific Gravity: 2.65; Fluorescence: Usually inert but can show weak green/blue under UV.
Optical Properties
Refractive Index: 1.544–1.553; Birefringence: 0.009; Optical Character: Uniaxial (+); Weak pleochroism in shades of purple/reddish-purple.
Hardness & Durability
Origin Region
Notable sources include Brazil (Rio Grande do Sul), Uruguay (Artigas), Madagascar, and Zambia. This specimen likely originates from a geode deposit.
Hardness & Durability
Mohs Hardness: 7; Toughness: Good; Highly stable for jewelry though susceptible to thermal shock.
Care & Maintenance
Clean with warm soapy water. Avoid ultrasonic cleaners and high heat. Keep out of prolonged direct sunlight to prevent color fading.
Rarity & Value
Common; value depends on color saturation (deeper purple is more valuable) and lack of visible inclusions. Often heat-treated to produce Citrine.
Special Characteristics
Displays distinct color zoning (alternating light and dark bands) and may contain fluid or 'tiger stripe' inclusions.
Lore & History
Ancient Greeks believed it prevented intoxication. Historically used in royal jewelry and religious ornaments. Culturally associated with the Third Eye/Crown chakras and tranquility.