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Ruby in Fuchsite is a striking metamorphic rock composed of green fuchsite (a chromium-rich variety of muscovite mica) with embedded crystals of red ruby (a chromium-rich variety of corundum). The vibrant green matrix provides a beautiful contrast to the often opaque to translucent pink to deep red ruby crystals, which can range from small specks to larger, well-formed hexagonal prisms. The rock often exhibits a schistose or gneissic texture due to the alignment of mica flakes.
How to Identify
- Color
- Dominantly green (fuchsite) with distinct pink to red (ruby) inclusions. The green can range from pale to emerald green, and the red from light pink to deep crimson.
- Luster
- Fuchsite exhibits a pearly to vitreous luster, while ruby can be vitreous to adamantine.
- Texture
- Often schistose or gneissic, with a flaky or platy appearance due to the mica. The ruby crystals are typically granular or prismatic within the matrix.
- Crystal Form
- Ruby crystals are typically hexagonal prisms, often anhedral to subhedral within the fuchsite matrix. Fuchsite forms platy, micaceous crystals.
- Cleavage
- Fuchsite has perfect basal cleavage (one direction), characteristic of micas. Ruby has no cleavage but exhibits parting.
- Geological Environment
- Found in medium to high-grade metamorphic terrains, particularly in areas where chromium-rich mafic or ultramafic rocks have undergone regional metamorphism. Often associated with greenstone belts or serpentinite bodies.
Key Facts
- Hardness: Fuchsite: 2.5-3 (Mohs); Ruby: 9 (Mohs)
- Specific Gravity: Fuchsite: 2.77-2.88; Ruby: 3.97-4.05
- Crystal System: Fuchsite: Monoclinic; Ruby: Trigonal
- Color: Green (fuchsite), Pink to Red (ruby)
- Luster: Pearly to vitreous (fuchsite), Vitreous to adamantine (ruby)
- Transparency: Fuchsite: Translucent to opaque; Ruby: Opaque to translucent (rarely transparent in this form)
- Fracture: Fuchsite: Uneven; Ruby: Conchoidal to uneven
- Cleavage: Fuchsite: Perfect basal (001); Ruby: None, but exhibits parting on {1011} and {0001}
- Composition: Fuchsite: K(Al,Cr)2(AlSi3O10)(OH)2 (Potassium aluminum chromium silicate hydroxide); Ruby: Al2O3 (Aluminum oxide with chromium impurity)
Quick Check
- Color: Green with red inclusions
- Luster: Pearly to vitreous (fuchsite), vitreous to adamantine (ruby)
- Streak: White (fuchsite), white (ruby)
Physical Characteristics
- Crystal Habit: Fuchsite: Micaceous, platy, foliated; Ruby: Prismatic, tabular, granular, often anhedral to subhedral within the matrix.
- Cleavage Type: Fuchsite: Perfect basal; Ruby: None (parting present)
- Fracture Type: Fuchsite: Uneven; Ruby: Conchoidal to uneven
- Tenacity: Fuchsite: Flexible, elastic; Ruby: Brittle
- Luster Type: Fuchsite: Pearly to vitreous; Ruby: Vitreous to adamantine
Formation
Ruby in Fuchsite forms during regional metamorphism of chromium-rich mafic or ultramafic rocks. The chromium content is crucial for the green color of fuchsite and the red color of ruby. During metamorphism, aluminum-rich protoliths (often altered mafic or ultramafic rocks) are subjected to high temperatures and pressures, leading to the crystallization of corundum (ruby) within a matrix of muscovite, which becomes fuchsite due to the incorporation of chromium.
Usage
Primarily used as an ornamental stone, for carvings, cabochons, spheres, and other lapidary applications. It is also popular in metaphysical and crystal healing communities. Due to the hardness contrast between ruby and fuchsite, it is generally not used for faceted gemstones unless the ruby inclusions are large and isolated enough to be cut independently.
Age Distribution
Typically found in Precambrian to Paleozoic metamorphic terrains, with specific ages varying by deposit.
Where to Find
India
Significant deposits are found in southern India, particularly in the Karnataka and Andhra Pradesh states, where it is mined for ornamental purposes.
Brazil
Occurrences have been noted in various metamorphic regions.
Russia
Found in certain metamorphic complexes.
Pakistan
Some deposits are known in the northern regions.
Norway
Reported in specific metamorphic localities.
Finding Tips
Look for Green and Red Contrast
The most distinctive feature is the vibrant green matrix with contrasting red inclusions. This color combination is unique to Ruby in Fuchsite.
Examine for Micaceous Texture
The fuchsite matrix will often show a characteristic flaky or platy texture due to its mica composition. Look for the pearly luster of the mica flakes.
Check Hardness
Ruby is very hard (9 on Mohs scale), while fuchsite is much softer (2.5-3). This difference can be felt when scratching the two components, though care should be taken not to damage specimens.
Consider Geological Context
Search in areas known for regional metamorphism of chromium-rich rocks, such as greenstone belts or serpentinite-associated terrains.
Similar Rocks
Ruby in Zoisite
Corundum (Ruby variety) in Zoisite with Hornblende
Also known as: Anyolite
Ruby in Kyanite
Corundum (Ruby variety) in Kyanite
Also known as: Ruby Kyanite
Fuchsite
K(Al,Cr)2(AlSi3O10)(OH)2
Also known as: Chromian Muscovite
Scientific Classification
- Mineral Class
- Fuchsite: Phyllosilicate (Mica Group); Ruby: Oxide (Corundum Group)
- Group
- Fuchsite: Muscovite subgroup; Ruby: Corundum
- Crystal System
- Fuchsite: Monoclinic; Ruby: Trigonal
- Chemical Formula
- Fuchsite: K(Al,Cr)2(AlSi3O10)(OH)2; Ruby: Al2O3 (with Cr3+ impurity)
- Composition
- Fuchsite is a potassium aluminum chromium silicate hydroxide. Ruby is aluminum oxide with trace amounts of chromium, which gives it its red color.
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