Fuchsite with Ruby

Metamorphic Rock (specifically a variety of schist or gneiss)

Chromian Muscovite with Corundum

Also known as: Ruby in Fuchsite, Chromian Muscovite with Corundum

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Description

Fuchsite with Ruby is a striking metamorphic rock composed primarily of green fuchsite (a chromium-rich variety of muscovite mica) with embedded crystals of red corundum (ruby). The vibrant green matrix of fuchsite provides a stark contrast to the often well-formed, hexagonal or barrel-shaped ruby crystals, making it a highly sought-after ornamental material. The fuchsite imparts a characteristic shimmering or aventurescent effect due to its platy habit.

How to Identify

Color: Vibrant green matrix (fuchsite) with distinct red to pinkish-red inclusions (ruby). White or grey minerals (e.g., kyanite, margarite) may also be present.
Luster: Fuchsite: Vitreous to pearly, often with a shimmering (aventurescent) quality. Ruby: Adamantine to vitreous.
Texture: Fuchsite: Foliated, schistose, or massive, often with a flaky or platy appearance. Ruby: Granular to well-formed hexagonal crystals embedded within the fuchsite matrix.
Crystal Form: Fuchsite: Micaceous, platy, often in aggregates. Ruby: Hexagonal prisms, barrel-shaped, or anhedral grains.
Cleavage: Fuchsite: Perfect basal cleavage (one direction). Ruby: No cleavage, but parting may be present.
Geological Environment: Medium- to high-grade metamorphic terrains, often associated with chromium-rich ultramafic rocks, serpentinites, or metasomatic zones.

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: Hexagonal (Trigonal)
Color: Fuchsite: Emerald-green; Ruby: Red to pinkish-red
Luster: Fuchsite: Pearly to vitreous; Ruby: Adamantine to vitreous
Transparency: Fuchsite: Translucent to opaque; Ruby: Transparent to opaque
Fracture: Fuchsite: Uneven; Ruby: Conchoidal to uneven
Cleavage: Fuchsite: Perfect basal (001); Ruby: None, but parting on {0001} and {1011} may be present
Composition: Fuchsite: K(Al,Cr)2(AlSi3O10)(OH)2; Ruby: Al2O3 (with Cr3+ impurity)

Quick Check

Color: Green (fuchsite) with red (ruby) inclusions
Luster: Pearly to vitreous (fuchsite), adamantine to vitreous (ruby)
Streak: White (fuchsite), white (ruby)

Physical Characteristics

Crystal Habit: Fuchsite: Micaceous, platy, foliated; Ruby: Prismatic, tabular, barrel-shaped, granular
Cleavage Type: Fuchsite: Perfect basal; Ruby: None (parting common)
Fracture Type: Fuchsite: Uneven; Ruby: Conchoidal to uneven
Tenacity: Fuchsite: Flexible, elastic; Ruby: Brittle
Luster Type: Fuchsite: Pearly to vitreous; Ruby: Adamantine to vitreous

Formation

Fuchsite with Ruby forms in medium- to high-grade metamorphic environments, often associated with ultramafic rocks or chromium-rich protoliths. The fuchsite (chromian muscovite) develops from the alteration of chromium-bearing minerals during regional metamorphism. The ruby (chromium-rich corundum) forms under specific conditions of aluminum-rich, silica-poor, and chromium-bearing environments, often within metasomatic zones or desilicated pegmatites and veins cutting through ultramafic rocks. The chromium content is crucial for both the green color of fuchsite and the red color of ruby.

Usage

Primarily used as an ornamental stone, for carvings, cabochons, spheres, and decorative objects. It is also popular among mineral collectors due to its striking color contrast and aesthetic appeal. It is not typically used for industrial purposes due to the relatively small size and irregular distribution of the ruby crystals.

Age Distribution

Typically found in Precambrian to Paleozoic metamorphic terrains, but specific ages vary by deposit.

Where to Find

India (Karnataka, Andhra Pradesh)

Significant deposits, particularly in the Mysore district of Karnataka, known for high-quality material.

Brazil (Bahia)

Known for occurrences of fuchsite with ruby, often associated with emerald deposits.

Russia (Ural Mountains)

Historical occurrences of fuchsite and ruby in metamorphic complexes.

Norway

Some occurrences reported in metamorphic rocks.

Pakistan

Occurrences in metamorphic belts.

Finding Tips

Geological Context

Look for areas with known occurrences of chromium-rich metamorphic rocks, such as serpentinites or altered ultramafic bodies. Regional metamorphic terrains are key.

Color and Luster

The distinctive green of fuchsite and the red of ruby are usually visible. The shimmering quality of fuchsite can be a good indicator.

Hardness Test

Ruby (9 on Mohs) is significantly harder than fuchsite (2.5-3 on Mohs). This difference can be used to distinguish the two minerals within the rock.

Associated Minerals

Often found with other metamorphic minerals like kyanite, margarite, and various amphiboles.

Similar Rocks

Zoisite with Ruby

Zoisite with Corundum

Also known as: Anyolite

Mica Schist

Various mica-rich metamorphic rocks

Also known as: Schist

Serpentinite

Serpentine Group Minerals

Also known as: Serpentine

Scientific Classification

Mineral Class: Fuchsite: Phyllosilicate (Mica Group); Ruby: Oxide (Corundum Group)
Group: Fuchsite: Muscovite subgroup; Ruby: Corundum
Crystal System: Fuchsite: Monoclinic; Ruby: Hexagonal (Trigonal)
Chemical Formula: Fuchsite: K(Al,Cr)2(AlSi3O10)(OH)2; Ruby: Al2O3:Cr
Composition: Fuchsite: Hydrous potassium aluminum silicate with significant chromium substitution for aluminum; Ruby: Aluminum oxide with chromium as the chromophore.

Explore Fuchsite with Ruby

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