El Choique, Argentina - Patagonian locality famed for pink amethyst geodes in late Cretaceous anhydrite, with quartz and calcite, sought by serious collectors.
Key facts
El Choique is the Patagonian locality that turned “pink amethyst” from a trade curiosity into a collector’s category with a documented geological home. The mine lies in Pehuenches Department, Neuquén Province, in northern Patagonia, where geode-bearing evaporitic rock has yielded quartz-lined cavities with an unusually delicate rose-to-purplish-pink color. The deposit is not a classic basalt-amethyst field like Artigas or Ametista do Sul; its collectible material is developed in late Cretaceous anhydrite, giving El Choique specimens a very different matrix, form, and mineral association from the South American amethyst geodes most collectors grew up with.
The fame of the locality rests on geodes lined with euhedral quartz crystals colored by the same broad amethystine iron-related mechanism, overprinted or accompanied by microscopic hematite that pushes the visual effect toward salmon, rose, mauve, or raspberry-pink rather than ordinary violet. Calcite is the great companion mineral: white, tan, brownish, or UV-reactive crystals perched on the pink quartz druse give the best pieces their strong sculptural contrast. Baryte, celestine, gypsum, analcime, and lithiophorite have also been documented, making the assemblage small but distinctive.
Historically, El Choique matters because it is a modern discovery whose entrance into the specimen world is well documented. The deposit was discovered in 2013, specimens reached the international market in 2017 at a Brazilian gem fair, and the material was given formal collector-mineralogical attention in a 2020 Mineralogical Record article by George R. Rossman, Ana L. Rainoldi, Lucas Di Martino, and Andrés Oteiza. That article did much to separate the Argentine material from vague marketplace labels such as “rose quartz,” “strawberry quartz,” and generic “pink quartz.”
Regional View
Country View
The best El Choique specimens have an unmistakable look: broken or sawn geode sections with a rind of pale evaporitic matrix, a sparkling interior of pink quartz points, and isolated calcite crystals standing up like white teeth or tan blades on the drusy surface. Fine pieces are judged less by sheer size than by freshness of color, unbruised terminations, balance between quartz and calcite, and whether the geode opened in a way that preserves a natural window into the pocket rather than a flat, decorative slab.
Photo:
Search for specimens: View all specimens from El Choique mine, Argentina
El Choique is recorded in Pehuenches Department, Neuquén Province, Argentina, at approximately 37° 36' 17" S, 69° 19' 54" W. The working is part of a geode-producing area in northern Patagonia southwest of Rincón de los Sauces, where provincial geological documentation describes quartz-geode mining files for Mina Choique and Mina Collicura in the Loma del Medio area. The provincial bulletin places these quartz-geode deposits about 40 km southwest of Rincón de los Sauces, with access from the Añelo–Rincón de los Sauces route system by provincial roads and gravel tracks toward the La Escalonada area.
The deposit type is best understood as a specimen-stone and gemological quartz-geode occurrence, not a metal mine. The collectible pockets occur in anhydrite, an evaporitic sulfate host rock, and the commercial product is the geode: a cavity lined inward by quartz, commonly followed by calcite and locally by accessory sulfate or zeolite minerals. This geological setting helps explain why El Choique pieces do not resemble the thick basalt geodes of Brazil and Uruguay. Instead of heavy basalt shells and deep purple druse, the Argentine material tends toward paler, more open geode fragments, pink to purplish-pink quartz linings, sulfate-rich associations, and calcite perched directly on the quartz.
The mineralization is cavity-controlled. The “ore bodies,” in collector terms, are geode-bearing horizons and pods in the anhydrite-bearing rock; the value is created only where open space allowed euhedral quartz crystals to grow. Subsequent or overlapping fluids introduced calcium carbonate as calcite and, in some pockets, barium and strontium sulfates as baryte and celestine. Gypsum and anhydrite belong naturally in this sulfate environment, while analcime and lithiophorite round out the documented mineral list. The pockets that matter to collectors are those in which the quartz grew as sharp, lustrous crystals rather than granular crusts, and where later calcite did not blanket or damage the pink druse.
The deposit was first discovered in 2013. By 2017, El Choique geodes had appeared on the international market at a gem fair in Brazil, and by 2020 the locality had received a full treatment in The Mineralogical Record. The 2022 Neuquén provincial bulletin identifies Andrés Oteiza as the title holder for the Loma del Medio quartz-geode deposits and gives a combined area of 359 hectares and 84 ares for the relevant mining files. The same bulletin notes the practical remoteness of the deposits: no local availability of gas, electricity, or water, no permanent housing or camp, and field crews generally working under temporary camp conditions during collecting seasons such as March and October.
Collecting access today should be considered closed to the public. The locality is on private property, and the recognized mine locality is not a casual rockhounding site. Specimens reach collectors through mine production, dealers, and the secondary market, not through public collecting. That matters for provenance: a strong El Choique label should name the mine, Pehuenches Department, Neuquén Province, Argentina, and ideally preserve the older “Choique” wording found on early dealer and publication labels.
The most notable finds are the geodes that preserved pink quartz with clean calcite. A published Mineralogical Record specimen shows an opened geode with pink amethyst and white calcite shortly after extraction at El Choique, and another published example shows pink amethyst crystals lining a 4 cm geode. Collector-gallery material also records 2019 finds of pink quartz geode fragments, pinecone- or rosette-like crystal groupings, and combinations of quartz, calcite, and baryte. These are the pieces that define the locality: fresh pocket surfaces, not merely cut decorative agate-like slices.
Calcite from El Choique is chiefly important as the architectural counterpoint to the pink quartz: white, cream, tan, and brownish crystals rise from the geode linings as isolated accents, small clusters, or more continuous drusy patches, and collector reports include scalenohedral to dogtooth-like forms as well as flatter, etched-looking crystals. The best pieces show calcite positioned naturally on lustrous pink amethystine quartz without overwhelming it, especially where a single white or warm-toned crystal sits near the center or rim of an opened geode; ordinary examples are merely calcite-dusted druse or broken geode fragments with little contrast. Some El Choique calcite is fluorescent, with peach, orange-pink, reddish, or yellowish responses reported under common longwave and shortwave UV lamps, but fluorescence varies by specimen and should be treated as an added feature rather than a guarantee.
El Choique amethyst is the locality’s signature mineral, but it is not the saturated purple cathedral-geode material familiar from Brazil or Uruguay; it is quartz lining small to moderate geodes in pale pink, rose, salmon, mauve, and purplish-pink tones, with the color tied to iron-related amethystine coloration and microscopic hematite particles. Crystals are typically euhedral points on cavity walls, locally forming sparkling druse, rosette-like groups, pinecone-like aggregates, and small geode interiors; published examples include a 4 cm geode and opened pockets carrying white calcite. The finest specimens combine even pink color, bright luster, sharp terminations, and a pleasing geode shape, preferably with calcite or baryte placed as a natural accent; weaker pieces are pale, granular, bruised, iron-stained, or too heavily cut and polished to retain a specimen character.
Quartz is the actual mineral species behind El Choique’s “pink amethyst,” and collectors should think of the locality as a quartz-geode occurrence with a remarkable color variety rather than as a separate mineral species. The quartz occurs as cavity linings in anhydrite, ranging from colorless or pale quartz and chalcedonic layers to the sought pink amethystine crystals, and some specimens show later associations with calcite, baryte, celestine, or thin chalcedony coatings. Good quartz specimens from El Choique are those in which the crystal form remains legible: sharp points, sparkling druse, rosette or pinecone groupings, and clean transitions between pink quartz and later minerals; ordinary examples lose their value when the quartz is merely a sugary crust, a broken lining, or a polished decorative fragment with no crisp crystals.
Other documented minerals from El Choique include analcime, baryte, celestine, gypsum, and lithiophorite. None is documented as a type-locality mineral species for the mine; the locality’s scientific importance lies instead in the unusual pink amethystine quartz and its well-described geode assemblage. Baryte is the most interesting accessory for collectors because it can occur with pink quartz and calcite in the same pocket, and reported UV observations include faint yellow response from baryte and greenish fluorescence along chalcedony-rich edges in some specimens. Celestine is mineralogically consistent with the sulfate-rich environment and adds strontium to the geode story, while gypsum and lithiophorite are more likely to interest locality-suite specialists than display collectors.
The major authenticity issue with El Choique is naming, not a famous wave of laboratory-made fakes. The material has been sold as “pink amethyst,” “rose quartz,” “strawberry quartz,” “red amethyst,” “hematite-included quartz,” and occasionally under vague Patagonia-only labels. For a serious collection, “quartz var. pink amethyst” or “pink amethystine quartz with microscopic hematite” is the most defensible style of label, with the mine locality stated separately. Avoid paying El Choique premiums for generic pink quartz carvings, Brazilian pink amethyst slabs, dyed agate, or unlabeled decorative geode pieces unless the seller can support the locality.
Provenance should be handled carefully because “Patagonia, Argentina” is not the same as El Choique. A strong label should read El Choique mine, Pehuenches Department, Neuquén Province, Argentina. Older labels may say Choique Mine or simply Choique, Pehuenches, Neuquén, and that usage is common in the trade. Be cautious with labels that drift to “El Chorrillo,” “Chiquada,” or other marketplace variants unless there is a clear reason; the well-documented scientific locality for this material is El Choique.
Condition is critical. Quartz points are hard, but the geodes are pocket specimens with exposed terminations that bruise easily along the high points. Calcite is much softer, has perfect cleavage, and commonly breaks at edges or tips; a dramatic calcite perched on pink quartz should be inspected for contact damage, glue, and repaired cleavage breaks. The pale sulfate-rich matrix can be crumbly, and associated gypsum or anhydrite argues against prolonged soaking. Avoid acids entirely because calcite will react, and avoid aggressive iron removers unless you are deliberately testing an inexpensive fragment and accept the risk of changing the specimen’s appearance.
UV response can add interest. Some El Choique calcite fluoresces in warm peach, orange-pink, reddish, or yellow tones depending on wavelength and specimen chemistry; some associated baryte or chalcedony-rich areas may also respond. Photographing these pieces under UV can be rewarding, but do not assume every specimen will fluoresce strongly. Because amethystine color can be affected by prolonged exposure to intense light, display fine pieces out of direct sun.
Market availability is better than that of many one-pocket modern discoveries, but high-grade specimens are much scarcer than decorative material. Small geode halves and fragments appear regularly, especially through crystal and mineral retailers, while sharp, saturated, publication-quality pieces with well-placed calcite are far less common. The sweet spot for advanced collectors is a miniature to small-cabinet geode that has not been over-trimmed, shows the pink quartz crystals clearly, and carries calcite or baryte as a natural association rather than as clutter.
The El Choique story has the feel of a modern mineral-market arrival: a new color of an old mineral, appearing suddenly enough that collectors had to decide what to call it while specimens were already changing hands. The deposit was discovered in 2013, but the wider collecting world met the material in 2017 at a gem fair in Brazil. That first public appearance mattered. Brazil is already the great South American marketplace for quartz geodes, so a pink geode material from Argentina was immediately both familiar and strange: it had the form language of amethyst, but the color of something collectors had been trained not to call amethyst.
The name argument came almost at once. Some dealers leaned into “pink amethyst,” because the specimens were plainly quartz crystals in geodes and had the visual drama of amethyst pockets. Others resisted the phrase because amethyst, in the strictest color sense, means purple quartz. The El Choique material occupied the uncomfortable middle: too crystal-lined and amethyst-like to be ordinary rose quartz, too pink to satisfy purists who wanted amethyst to stay violet. Caltech analytical work and the 2020 Mineralogical Record article gave collectors a more stable footing by describing the material as purplish-pink amethystine quartz with additional coloring from microscopic hematite particles. In practical collector language, that made “pink amethyst” acceptable when used as a variety or trade name rather than as a new mineral species.
The mine itself adds a second, less romantic but equally memorable layer. Neuquén’s provincial gemological bulletin describes the Loma del Medio geode deposits as remote workings without gas, electricity, water, or permanent housing. When collecting is carried out, crews camp in tents, with field activity generally noted for months such as March and October. That detail helps explain the character of the specimens: these are not anonymous factory-polished decorator pieces from an industrial geode belt, but products of a specific Patagonian sulfate-hosted deposit where each good pocket had to be found, opened, trimmed, and carried out under field conditions.
A published EarthWonders record preserves one of the strongest visual moments from the mine: an opened geode containing pink amethyst and white calcite photographed shortly after extraction by Lucas Di Martino and reproduced as Figure 14 in The Mineralogical Record. It is the sort of image that tells the locality in one glance. The pocket is fresh, the quartz is pink rather than merely stained, and the white calcite sits in the cavity like a punctuation mark. For collectors, that is the El Choique ideal.
