Aragonite

Extended geology

Aragonite is a carbonate mineral with the formula CaCO₃, a polymorph of calcite. It crystallizes in the orthorhombic system, space group Pmcn (sometimes written Pnma depending on axis choice). Typical habit is pseudohexagonal twin clusters (the classic "sputnik" form from Morocco), radiating fibrous or acicular masses, short prisms with bevelled terminations, or flowstone and stalactitic forms in caves. Cleavage is distinct on {010} and poor on {110}. Fracture is subconchoidal to uneven. Luster is vitreous to resinous on fresh surfaces.

Physical properties: Mohs hardness 3.5 to 4. Specific gravity 2.93 to 2.95, notably higher than calcite's 2.71, which is a useful distinguishing test in hand. Refractive index 1.530 to 1.685 with high birefringence (0.155). Dispersion 0.026. Pleochroism is weak. Aragonite is metastable at surface temperatures and pressures, meaning that given geological time it will slowly invert to the more stable calcite structure. Many ancient aragonite deposits have fully converted, which is why most prehistoric shell material in the fossil record is now calcite.

Color chemistry: pure aragonite is colorless to white. The red and orange tones in Peruvian material come from trace ferric iron (Fe³⁺) and iron oxide inclusions. Brown reflects mixed iron and organic staining. Blue aragonite, which surfaces occasionally from Africa, is colored by trace copper. The coloration sits in thin layers or dispersed grains rather than in the primary lattice, which is why natural pieces often show mottling, banding, and zoning rather than uniform tone. Biogenic aragonite (nacre, coral, some mollusk shells) is built of the same mineral with different trace-element and organic-matrix chemistry.

Extended sourcing

Peru is a source of rough and tumbled red and brown aragonite for the North American wholesale market. The material originates in the Junín region of the central Andes, where carbonate-rich sedimentary units host aragonite veins and cave-fill deposits. Extraction is predominantly small-scale and artisanal, using hand tools and surface collection from quarry faces and cave vugs. Material moves from extractors through consolidators to exporters, then to brokers and wholesalers abroad. Mine-level traceability is unusual at the wholesale stage and is rarely verified when claimed.

Morocco supplies the iconic pseudohexagonal twin clusters, known in the trade as "sputnik aragonite" or "star aragonite," from the Tazouta and Midelt regions. These form in oxidized lead-zinc orebodies and are extracted primarily for the collector and crystal markets. Morocco's sputnik material is among the most counterfeited aragonite in the global market, with reconstructed or reglued specimens common in the trade; look closely for glue seams where the crystals meet.

Spain is the type locality: Abraham Gottlob Werner described and named the mineral in 1797 from samples collected near Molina de Aragón, in the province of Guadalajara. Historic specimen material from Molina de Aragón and Minglanilla remains in collector circulation. The Czech Republic, Mexico (Guanajuato, Sonora), Namibia (Tsumeb, where the copper-blue variety has been documented), China (Guizhou, Hubei), and the United States (caves and hot-spring deposits in Virginia, New Mexico, Arizona, and Nevada) also contribute commercial and specimen-grade material.

Our supply: our aragonite traces through a single-channel partner. We confirm country and region at the batch level. We do not claim individual mine sites because the consolidator stage of the trade makes that claim unreliable. Material with incomplete documentation is held back rather than listed.

Authentication and warning signs

Natural aragonite in the Peruvian trade is mottled and uneven by default. Red pieces show banded or patchy iron coloration, often with paler cream or brown zones. Brown pieces shade from warm tan through deeper chocolate, with visible fibrous or radiating structure in some specimens. A 2-inch tumbled stone in a perfectly uniform saturated red should be treated with suspicion. Dye tends to concentrate along edges, inside fractures, and on the inner surfaces of cleavage breaks. If the color runs deeper in the damaged areas than on the polished surface, dye is the likely cause.

Hardness and gravity tests: aragonite scratches easily with a steel knife or needle (5.5), is not scratched by a copper coin (about 3), and will not scratch glass. Specific gravity in hand feels heavier than calcite for the same size. A small drop of dilute hydrochloric acid produces strong effervescence (both aragonite and calcite do this). Under ultraviolet long-wave light, some aragonite varieties fluoresce pink, creamy white, or yellow; calcite typically fluoresces red or orange.

Warning signs in the wider market: uniform deep saturation across large tumbled pieces (likely dyed), dramatic color flashes in banded stones that suggest surface coating rather than natural layering, Moroccan sputnik clusters with visible seams or mismatched crystals (signs of glued or reassembled specimens), and any seller who cannot state country of origin when asked. Much of the blue material sold under the aragonite name is dyed howlite, magnesite, or quartz; dye tends to gather in cracks and leave white showing at chips and drill holes.

Historical and cultural context

The name aragonite was formalized by Abraham Gottlob Werner in 1797, based on specimens from Molina de Aragón in central Spain. Before Werner's description, the mineral had been confused with calcite for centuries, since both share the same chemistry. The structural distinction between the two polymorphs was only resolved in the early nineteenth century through crystallographic work by René Just Haüy and others.

Biological aragonite has a much older human story. Mollusk shells, coral skeletons, and the nacre layer of pearl oysters are all aragonite, and all have been traded, carved, and used ornamentally for thousands of years. The biogenic forms converted slowly to calcite in deep geological time, which is why most fossil shell material is now calcite rather than aragonite. Living coral reefs and modern seashells remain the largest reservoir of aragonite on the planet.

Modern crystal associations for aragonite emerged in the late twentieth century as crystal healing literature consolidated around elemental and chakra correspondences. Unlike aquamarine or amethyst, aragonite has no substantial ancient or medieval lore, and any source claiming otherwise is importing narrative from other stones.

Varieties and trade names

Red Aragonite: iron-rich Peruvian material, most commonly hand-polished or tumbled.

Brown Aragonite: mixed iron and organic coloration. Sold in both hand-polished and raw forms.

Sputnik Aragonite (also Star Aragonite): pseudohexagonal twin clusters from Morocco. Specimen-grade material with a distinctive radiating three-axis habit.

Blue Aragonite: copper-bearing aragonite, rare and typically sourced from African or Chinese localities. Collector material. Frequently faked with dyed howlite or magnesite.

Flos Ferri (Flower of Iron): fragile white coralloidal aragonite from iron-ore deposits, particularly Eisenerz, Austria. Historically prized as a mineralogical curiosity.

Cave Aragonite (also Flowstone, Helictite): aragonite forms in cave systems worldwide, often in delicate branching helictite structures that defy gravity due to capillary action during growth. Extraction from active caves is restricted in most jurisdictions.

Onyx Aragonite (Calcareous Onyx): banded aragonite marketed as onyx, particularly from Mexican and Moroccan sources. Not the same as true onyx (banded chalcedony).

Pricing reality

Raw Grade A brown aragonite sits at the entry level. Hand polishing moves Grade AA brown aragonite up a step, and hand-polished Grade AAA red aragonite costs more again, depending on size, color saturation, and finish. Moroccan sputnik clusters cover a wide range set by cluster size, symmetry, and undamaged terminations, and large specimen clusters and showpieces reach collector level.

Tumbled blue aragonite generally sits above brown in value, though much of the market is mislabeled dyed material. Verified copper-blue aragonite crystal specimens sit in the collector range. Fossil coral and nacre products (mother-of-pearl, ammolite) price on their own curves and are not directly comparable to mineral aragonite.

Value drivers: color saturation, natural patterning, size, cluster symmetry for sputnik material, and documented origin. Warning signs: uniform saturated red with no natural patterning, Moroccan sputnik with visible seams or mismatched crystals (usually glued or reconstructed), and blue aragonite that shows white at chips or drill holes.