Ruby in Fuchsite

Description

Ruby in Fuchsite is a striking metamorphic rock composed of red corundum (ruby) crystals embedded within a green chromian muscovite (fuchsite) matrix. The ruby crystals typically appear as opaque to translucent, hexagonal or anhedral grains, ranging in color from pinkish-red to deep crimson. The fuchsite matrix provides a vibrant emerald-green backdrop, often with a shimmering, micaceous luster. Minor accessory minerals such as kyanite, margarite, rutile, and various amphiboles may also be present.

How to Identify

Color

Distinctive combination of opaque to translucent red (ruby) and vibrant emerald-green (fuchsite).

Luster

Ruby is sub-adamantine to vitreous; fuchsite is pearly to vitreous.

Texture

Granular to schistose, with visible ruby crystals embedded in a micaceous matrix.

Crystal Form

Ruby typically forms hexagonal prisms or anhedral grains; fuchsite forms platy, micaceous aggregates.

Cleavage

Ruby has no cleavage (parting may be present); fuchsite exhibits perfect basal cleavage (001).

Geological Environment

Metamorphic terrains, particularly those associated with chromium-rich mafic or ultramafic protoliths, often found in greenschist to amphibolite facies metamorphic rocks.

Key Facts

• Hardness: Ruby: 9 (Mohs); Fuchsite: 2.5-3 (Mohs)
• Specific Gravity: Ruby: 3.95-4.10; Fuchsite: 2.77-2.88
• Crystal System: Ruby: Trigonal; Fuchsite: Monoclinic
• Color: Ruby: Red to pinkish-red; Fuchsite: Emerald-green
• Luster: Ruby: Sub-adamantine to vitreous; Fuchsite: Pearly to vitreous
• Transparency: Ruby: Opaque to translucent; Fuchsite: Translucent to opaque
• Fracture: Ruby: Conchoidal to uneven; Fuchsite: Uneven
• Cleavage: Ruby: None (parting on {0001} and {1011}); Fuchsite: Perfect basal cleavage on {001}
• Composition: Ruby: Aluminum oxide (Al2O3) with trace chromium; Fuchsite: Hydrous potassium aluminum silicate with chromium (K(Al,Cr)2(AlSi3O10)(OH)2)

Quick Check

• Color: Red (ruby) and green (fuchsite)
• Luster: Ruby: sub-adamantine to vitreous; Fuchsite: pearly to vitreous
• Streak: Ruby: white; Fuchsite: white

Physical Characteristics

• Crystal Habit: Ruby: Hexagonal prisms, tabular, or anhedral grains; Fuchsite: Micaceous, platy, foliated aggregates
• Cleavage Type: Ruby: None (parting); Fuchsite: Perfect basal cleavage
• Fracture Type: Ruby: Conchoidal to uneven; Fuchsite: Uneven
• Tenacity: Ruby: Brittle; Fuchsite: Flexible, elastic
• Luster Type: Ruby: Sub-adamantine to vitreous; Fuchsite: Pearly to vitreous

Formation

Ruby in Fuchsite forms through regional or contact 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 minerals react with chromium-bearing fluids or minerals to form corundum (ruby), while potassium, aluminum, and chromium-rich fluids or minerals form fuchsite. The process often involves metasomatism, where chemical alteration occurs due to the introduction of fluids.

Usage

Primarily used as an ornamental stone, for carvings, cabochons, spheres, and decorative objects. It is also popular in lapidary arts and as a collector's mineral specimen. Due to the contrasting colors and hardnesses, it is not typically used for faceted jewelry.

Age Distribution

Typically associated with Precambrian to Paleozoic metamorphic events, though specific ages vary by deposit.

Where to Find

Finding Tips

Similar Rocks

Scientific Classification

Mineral Class

Ruby: Oxide; Fuchsite: Phyllosilicate (Mica Group)

Group

Ruby: Corundum Group; Fuchsite: Muscovite Subgroup

Crystal System

Ruby: Trigonal; Fuchsite: Monoclinic

Chemical Formula

Ruby: Al2O3 (with Cr3+ substitution); Fuchsite: K(Al,Cr)2(AlSi3O10)(OH)2

Composition

Ruby: Aluminum oxide with chromium impurities; Fuchsite: Hydrous potassium aluminum silicate with significant chromium substitution for aluminum.

Explore Ruby in Fuchsite