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          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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