Aragonite
Aragonite (variety Flos Ferri or brown aragonite) · Mineral Specimen / Decorative Stone
Crystal System
Orthorhombic; typically found in pseudo-hexagonal prismatic habits (often twinned), tabular or acicular forms, and massive aggregates.
Mineral Group
Carbonates (Aragonite Group)
Chemical Formula
CaCO3 (Calcium Carbonate with possible trace Manganese or Iron)
Formation Process
Formed through low-temperature sedimentary processes, precipitation from hot springs or hydrothermal vents, or as biological secretions in mollusk shells (nacre).
About This Crystal
Medium-brown to reddish-brown translucent specimen with a vitreous to resinous luster. It exhibits a blocky or tabular habit with visible cleavage planes and a somewhat stepped surface texture.
Physical Characteristics
Color: Brownish-red to tan; Streak: White; Cleavage: Distinct on [010]; Fracture: Subconchoidal; Specific Gravity: 2.93–2.95; Fluorescence: Often fluoresces yellow or cream under LW-UV.
Optical Properties
Biaxial negative; Refractive Index: nα = 1.529, nβ = 1.680, nγ = 1.685; Birefringence: 0.156; No significant pleochroism in most brownish specimens.
Hardness & Durability
Origin Region
Molina de Aragón, Spain (type locality); Tsumeb, Namibia; Karlovy Vary, Czech Republic; and various limestone caves globally.
Hardness & Durability
Mohs Hardness: 3.5–4.0; Brittle tenacity; poor durability for jewelry as it is susceptible to scratching and acid erosion.
Care & Maintenance
Avoid all acids (will effervesce); clean only with lukewarm soapy water; store away from harder minerals like quartz; avoid ultrasonic cleaners which may shatter the stone.
Rarity & Value
Relatively common; value is determined by crystal form and transparency. Massive brown specimens are inexpensive, while well-formed twinned crystals are highly sought by collectors.
Special Characteristics
Displays strong double refraction and effervesces (bubbles) vigorously when in contact with dilute hydrochloric acid. It is a polymorph of Calcite.
Lore & History
First discovered in 1797 in Aragon, Spain. Historically used as a source of lime. Metaphysically associated with grounding, patience, and stabilizing the root and earth star chakras.