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Charoite is a rare and complex hydrous potassium-calcium-sodium silicate mineral, characterized by its distinctive vibrant purple to lilac color, often with swirling patterns of black (aegirine), orange (tinaksite), and white (microcline or feldspar). Its unique fibrous structure gives it a chatoyant or shimmering effect when polished. It is found exclusively in the Murun Massif in Siberia, Russia.
How to Identify
- Color
- Vibrant purple, lilac, lavender, often with swirling patterns of black, orange, and white.
- Luster
- Vitreous to silky, especially on fibrous surfaces.
- Texture
- Fibrous, often intergrown, giving a swirling or chatoyant appearance when polished.
- Crystal Form
- Typically massive, compact, or fibrous aggregates. Individual crystals are rare and microscopic.
- Cleavage
- Perfect on {100} and {010}, but rarely observed due to its fibrous nature.
- Geological Environment
- Exclusively found in metasomatic rocks formed at the contact zone between alkaline intrusions (syenites) and carbonate rocks (limestone/dolomite).
Key Facts
- Hardness: 5-6 on the Mohs scale
- Specific Gravity: 2.54-2.68
- Crystal System: Monoclinic
- Color: Purple, lilac, lavender, often with black, orange, and white inclusions
- Luster: Vitreous to silky
- Transparency: Translucent to opaque
- Fracture: Uneven to splintery due to fibrous nature
- Cleavage: Perfect on {100} and {010}, but rarely observed
- Composition: Hydrous potassium-calcium-sodium silicate with hydroxyl and fluorine
Quick Check
- Color: Purple to lilac with swirling patterns
- Luster: Vitreous to silky
- Streak: White
Physical Characteristics
- Crystal Habit: Massive, compact, fibrous aggregates, often radiating or intergrown.
- Cleavage Type: Perfect on {100} and {010}, but typically not visible in massive material.
- Fracture Type: Uneven to splintery.
- Tenacity: Brittle.
- Luster Type: Vitreous to silky.
Formation
Charoite forms exclusively in a unique geological environment: the contact zone between a syenite intrusion and a limestone-dolomite sequence, where it undergoes metasomatic alteration. This process involves the replacement of original minerals by new ones due to the introduction of hot, chemically active fluids. The presence of potassium, calcium, sodium, silicon, and hydroxyl/fluorine ions in these fluids, along with specific temperature and pressure conditions, are critical for charoite crystallization. It is often found associated with other rare minerals such as tinaksite, canasite, and fedorite.
Usage
Primarily used as an ornamental stone, for carvings, cabochons, beads, and other lapidary applications due to its striking color and unique fibrous texture. It is also collected by mineral enthusiasts.
Age Distribution
Formed during the Mesozoic Era, approximately 130-140 million years ago.
Where to Find
Murun Massif, Sakha Republic (Yakutia), Russia
The only known locality for charoite in the world. It occurs in a unique geological setting within the Murunsky alkaline complex, where it forms large, lens-shaped bodies within metasomatic rocks.
Finding Tips
Authenticity
Due to its rarity and value, be wary of imitations. Genuine charoite will have a distinct fibrous texture and often exhibit chatoyancy.
Associated Minerals
Look for associated minerals like tinaksite (orange-brown), canasite (pinkish-purple), aegirine (black), and microcline (white) which often occur within charoite specimens.
Source Verification
Always purchase from reputable dealers who can verify the origin of the material from the Murun Massif.
Similar Rocks
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KNa2(Fe,Mn,Al)2Li3Si12O30
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Amethyst
SiO2
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Lepidolite
K(Li,Al)3(Al,Si,Rb)4O10(F,OH)2
Also known as: Lithium Mica
Scientific Classification
- Mineral Class
- Silicates
- Group
- Inosilicates (chain silicates)
- Crystal System
- Monoclinic
- Chemical Formula
- K(Ca,Na)2Si4O10(OH,F)·H2O
- Composition
- Potassium calcium sodium silicate hydroxide fluoride hydrate
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