Aragonite Value, Price, and Jewelry Information

Triangle-cut aragonite, 22.19 cts, 22 x 19.3 mm, Czech Republic. © The Gem Trader. Used with permission.

Aragonite

Aragonite is more commonly found as a constituent of pearl and shell nacre than as a crystal suitable for gem cutting. Too soft for most jewelry use, a faceted aragonite would be a true collector’s item.

Aragonite Value

The International Gem Society (IGS) has a list of businesses offering gemstone appraisal services.

Aragonite Value via Gem Price Guide

Accompanying value information:
Not found
Faceted 5 carats plus
to /ct

Aragonite Information

Data Value
Name Aragonite
Crystallography Orthorhombic. Pseudo hexagonal, crystals often acicular, chisel-shaped, prismatic; also massive columnar, fibrous, stalactitic, coralloidal. Frequently twinned.
Refractive Index 1.530-1.685
Colors Colorless, white, yellow, gray, green, blue-green, lavender, reddish, brown.
Luster Vitreous to resinous
Hardness 3.5-4
Fracture Subconchoidal
Specific Gravity 2.947 (pure). Usually 2.93 – 2.95; up to 3.0 if Pb present.
Birefringence 0.155
Cleavage Distinct 1 direction
Luminescence See "Identifying Characteristics" below.
Luminescence Present Yes
Luminescence Type Fluorescent, Phosphorescent, UV-Long, UV-Short
Transparency Opaque to transparent
Absorption Spectrum Not diagnostic
Formula CaCO3 + Pb, Sr, rarely Zn.
Pleochroism None
Optics α = 1.530; β = 1.681; γ = 1.685. Biaxial (-), 2V = 18°. Sector twinning observed.
Optic Sign Biaxial -
Etymology After the locality Molina de Aragon, Spain, where the material was first identified.
Occurrence Worldwide, especially in limestone caverns, hot springs, and in the oxidized zone of ore deposits.
Inclusions Usually veil-type inclusions observed.
aragonites - Slovakia

Aragonites, spray of crystals on matrix, Podrescany, Lucsenac, Slovakia. © Rob Lavinsky, www.iRocks.com. Used with permission.

Comments

Aragonite and calcite are dimorphous or polymorphs. They share the same chemistry but have different crystal habits. While calcite is the most abundant and widespread carbonate mineral on Earth, aragonite is less so. Facetable aragonites are almost always very small, as opposed to calcites, which occur in huge, transparent masses or crystals. (Like calcites, aragonites have a high birefringence and will also show facet doubling).

Be aware that some people describe ammolite as aragonite. However, this mineral only constitutes a part (albeit major) of this fossilized shell gem material.

Identifying Characteristics

Luminescence

  • Longwave: Pale rose, yellow, tan, green, rarely bluish; also may phosphoresce green (Sicily).
  • Shortwave: Yellowish, pinkish-red, tan, and white; also pink (Sicily).
aragonite - fluorescence

Aragonite from the Santa Eulalia mine in Chihuahua, Mexico, under daylight (above) and shortwave ultraviolet light (below). Photo by Hadley Paul Garland. Licensed under CC By-SA 2.0.

Enhancements

Heating to 400° C will convert aragonite into calcite. This occurs naturally over millions of years, but no commercial incentive exists to do this in a lab.

Sources

Notable gem sources include:

  • Spain: Molina de Aragon, type locality, in stubby twinned crystals.
  • Czech Republic: Bilin.
  • Greece: Laurium, blue aragonite.
  • Sicily: Agrigento, with sulfur crystals.
  • Chile: blue material.
  • Mexico: Guanajuato.
  • United States: Many localities, including Colorado, New Mexico, South Dakota, and Virginia. California, Iowa, and Wyoming yield a fibrous variety.
  • Austria; Germany; Namibia; Peru; Slovakia; United Kingdom.
aragonites - Spain

Aragonite, Retamal ravine, Enguidanos, Cuenca, Castile-La Mancha, Spain. Photo by Didier Descouens. Licensed under CC By 4.0.

Stone Sizes

Faceted gems are usually only a few carats and colorless, but the potential exists for much larger stones. The largest known cut specimen hails from Bilin, Czech Republic: a straw-yellow emerald-cut gem that weighs 110 carats.

Straw-yellow crystals from Horschenz, Germany have yielded stones up to 10 carats.

The Devonian Group in Calgary, Alberta, Canada holds a 7.85-ct stone from Germany.

Care

Aragonite’s hardness is too low for this stone to be worn safely in jewelry. Avoid mechanical cleaning such as steam or ultrasonic processes. Instead, use a soft brush, mild detergent, and warm water for cleaning. Store your aragonites separately from other stones to avoid contact scratches. Consult our gemstone jewelry cleaning guide for more recommendations.

aragonite - Czech Republic

Aragonite: Czech Republic (5.35). Photo © Joel E. Arem, PhD, FGA. Used with permission.

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