Got a photo? Identify rocks instantly with the Rockby app
Open the appDescription
Charoite is a rare and complex hydrous potassium-calcium-sodium silicate mineral, characterized by its vibrant purple to lilac color and distinctive swirling, fibrous, or feathery patterns. It often exhibits chatoyancy, a silky luster, and can contain inclusions of other minerals such as tinaksite, canasite, and microcline, which contribute to its unique appearance. It is found exclusively in one location globally.
How to Identify
- Color
- Vibrant purple, lilac, lavender, or violet, often with swirling patterns of white, black, or orange inclusions.
- Luster
- Vitreous to silky, often chatoyant.
- Texture
- Fibrous, swirling, or feathery patterns, often with a distinct 'shimmer' due to chatoyancy.
- Crystal Form
- Typically massive, forming aggregates of intergrown fibrous crystals. Individual crystals are rarely well-formed and are usually microscopic.
- Cleavage
- Perfect on {100}, but rarely observed due to its fibrous habit.
- Geological Environment
- Exclusively found in metasomatic rocks formed at the contact zone between syenite intrusions and limestone/dolomite, under specific high-pressure, low-temperature conditions.
Key Facts
- Hardness: 5-6 on the Mohs scale
- Specific Gravity: 2.54-2.78
- Crystal System: Monoclinic
- Color: Purple, lilac, lavender, violet, often with white, black, or orange inclusions
- Luster: Vitreous to silky, chatoyant
- Transparency: Translucent to opaque
- Fracture: Uneven to splintery
- Cleavage: Perfect on {100}, but rarely observed due to fibrous habit
- Composition: Hydrous potassium-calcium-sodium silicate
Quick Check
- Color: Purple to lilac with swirling patterns
- Luster: Silky to vitreous, often chatoyant
- Streak: White
Physical Characteristics
- Crystal Habit: Massive, fibrous, radiating, or felted aggregates. Individual crystals are acicular (needle-like) but typically intergrown.
- Cleavage Type: Perfect on one direction ({100}), but often obscured by its fibrous nature.
- Fracture Type: Uneven to splintery, reflecting its fibrous structure.
- Tenacity: Brittle
- Luster Type: Vitreous to silky, often exhibiting chatoyancy (cat's-eye effect) due to its fibrous structure.
Formation
Charoite forms exclusively in a unique geological setting: the contact zone between syenite intrusions and limestone/dolomite deposits, under specific conditions of high pressure and low temperature metasomatism. It is a product of alkali-rich fluid interaction with carbonate rocks, leading to the replacement of original minerals by charoite and associated minerals. The presence of potassium, calcium, sodium, silicon, and hydroxyl/fluorine is crucial for its formation. The characteristic fibrous texture is a result of its growth within these metasomatic veins.
Usage
Primarily used as an ornamental stone, for carvings, cabochons, beads, and other lapidary applications due to its striking color and chatoyancy. 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), Siberia, Russia
The only known locality for charoite in the world. It occurs in the Chara River region, from which it derives its name. The deposit is associated with the Murunskii alkaline massif, where syenite intrusions have metasomatically altered carbonate rocks.
Finding Tips
Authenticity
Due to its rarity and unique appearance, charoite is sometimes imitated. Look for the characteristic swirling fibrous texture and chatoyancy. Be wary of overly uniform color or lack of natural inclusions.
Associated Minerals
Charoite often occurs with other rare minerals such as tinaksite (yellow-brown), canasite (pink-violet), microcline (white/pink), and aegirine (black), which can help in identification and confirm its origin.
Handling Precautions
Charoite is a silicate mineral and generally safe to handle. However, as with any mineral, avoid inhaling dust if cutting or polishing, and wash hands after handling. There are no known toxic elements in its primary composition that pose a significant risk under normal handling.
Similar Rocks
Sugilite
KNa2(Fe,Mn,Al)2Li3Si12O30
Also known as: Luvulite
Amethyst
SiO2
Also known as: Purple Quartz
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), though its complex structure can also be described as a layered silicate with chain-like elements.
- Crystal System
- Monoclinic
- Chemical Formula
- K(Ca,Na)2Si4O10(OH,F)·nH2O
- Composition
- Potassium calcium sodium silicate hydroxide fluoride hydrate. The 'n' in nH2O indicates a variable amount of water.
Explore Charoite
Identify rocks anywhere
Free on iOS, Android, and Web. Photo identification, full database, and your personal collection.