The acanthite crystals from this mine located near Guanajuato, Mexico, are world-renowned. The specimens we occasionally find for sale are usually aggregates of cubic-shaped crystals. This specimen we offer stands out for its centimeter-sized, highly defined crystal, with the usual cube faces truncated by the octahedron. The metallic luster is very good and it is arranged airily on a matrix formed by small, hyaline quartz crystals. An exceptional and ancient piece...

Brilliant, gem-like, well-defined aquamarine-blue celestine crystals are disposed in aesthetic contrast on a matrix covered with snowy white colemanite crystals. A piece of exceptional aesthetics from a locality known for its borates, but from which few specimens of this type have been seen.

Brilliant, gem-like, well-defined aquamarine-blue celestine crystals are disposed in aesthetic contrast on a matrix covered with snowy white colemanite crystals. A piece of exceptional aesthetics from a locality known for its borates, but from which few specimens of this type have been seen.

Highly aesthetic botryoidal malachite aggregates completely covered by a layer of slightly greenish-blue chrysocolla. We can see the malachite, with concentric growths, in some fractures. The beauty of these specimens makes them worthy of the finest collection and display case.

Very aesthetic botryoidal malachite aggregates completely covered by a layer of blue chrysocolla. We can see the malachite, with concentric growths, in some fractures. The beauty of these specimens makes them worthy of the finest collection and display case.

Highly aesthetic botryoidal malachite aggregates completely covered by a layer of slightly greenish-blue chrysocolla. We can see the malachite, with concentric growths, in some fractures. The beauty of these specimens makes them worthy of the finest collection and display case.

These specimens from the Turó de Montcada quarry are characterized by a breccia-like appearance formed by ampelitic slate cemented with variscite, thanks to the hydrothermal fluids that circulated between them. It shows a polished section that can allow us to observe different colour tones, between green and white. We can observe folds called stigmatic, produced by the entry of a viscous fluid (variscite) into a less viscous one. This led us to consider the possibility of an alteration of the variscite that had converted it into crandallite, but X-ray diffraction studies determined that it was dehydrated variscite with minor strengite. We will send the analytical results to the buyer.

60 €

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These specimens from the Turó de Montcada quarry are characterized by a breccia-like appearance formed by ampelitic slate cemented with variscite, thanks to the hydrothermal fluids that circulated between them. It shows a polished section that can allow us to observe different colour tones, between green and white. This led us to consider the possibility of an alteration of the variscite that had converted it into crandallite, but X-ray diffraction studies determined that it was dehydrated variscite with minor strengite. We will send the analytical results to the buyer.

40 €

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These specimens from the Turó de Montcada quarry are characterized by a breccia-like appearance formed by ampelitic slate cemented with variscite, thanks to the hydrothermal fluids that circulated between them. It shows a polished section that can allow us to observe different colour tones, between green and white. This led us to consider the possibility of an alteration of the variscite that had converted it into crandallite, but X-ray diffraction studies determined that it was dehydrated variscite with minor strengite. We will send the analytical results to the buyer.

55 €

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These specimens from the Turó de Montcada quarry are characterized by a breccia-like appearance formed by ampelitic slate cemented with variscite, thanks to the hydrothermal fluids that circulated between them. It shows a polished section that can allow us to observe different colour tones, between green and white. This led us to consider the possibility of an alteration of the variscite that had converted it into crandallite, but X-ray diffraction studies determined that it was dehydrated variscite with minor strengite. We will send the analytical results to the buyer.

50 €

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A good-sized tremolite crystal, transparent and with defined faces, doubly terminated. The prism has a rhombus cross-section. Specimens of tremolite from this Afghan locality are highly prized for their gem quality.

In this specimen we can observe an idiomorphic good size crystal of tapiolite-(Fe), Fe²⁺Ta₂O₆, that shows us different tetragonal faces. Good luster, intense black colour with iridescence on faces. It stands out on a matrix with albite and muscovite. The analyzes carried out indicate the presence of niobium in small proportions. These results will be sent to the buyer of the specimen.

Reserved

A group of brilliant pseudohexagonal chalcocite crystals, one of which stands out for its size and definition. These specimens, considered among the finest in the world, come from the M'Passa mining area in the Republic of the Congo, near the border with the Democratic Republic of the Congo. Many of the mining operations closed in the 1980s, but new workings have yielded exceptional specimens like this one.

Intense green paratacamite crystals from a Chilean mine where the species has been well identified. The crystals are prismatic, sharp, lustrous, and transparent. A very good specimen for the species.

A rich druse formed by tarbuttite crystals, Zn₂(PO₄)(OH). They're very brilliant, transparent, and with well defined faces and edges. Kabwe is the type locality for the species. It was acquired from Dr. Viñals.

Reserved

Specimen formed by various aggregates of sheaf-shaped ushkovite crystals, with a distinctive orange color. It is a rare phosphate with the formula MgFe³⁺₂(PO₄)₂(OH)₂·₈H₂O. They are arranged on a matrix of roscherite and rockbridgeite, with white crusts of uralolite and possibly small colorless beryllonite crystals. A very interesting specimen due to the rarity of the minerals present.

Reserved

These specimens were acquired and identified by the remembered Dr. Joan Viñals (1951-2013), who brought them back from a trip to Chile in the early 2000s. We can see radial aggregates of parasymplesite, Fe²⁺₃(AsO₄)₂·8H₂O, which, according to the label, are intensely lustrous and blue-green in color. They are most likely accompanied by symplesite. A representative specimen from the E. Nicolau collection (Barcelona).

Reserved

These specimens were acquired and identified by the remembered Dr. Joan Viñals (1951-2013), who brought them back from a trip to Chile in the early 2000s. We can see radial aggregates of parasymplesite, Fe²⁺₃(AsO₄)₂·8H₂O, which, according to the label, are intensely lustrous and blue-green in color. They are most likely accompanied by symplesite. A representative specimen from the E. Nicolau collection (Barcelona).

Reserved

Leightonite is a rare copper sulfate with calcium and potassium, K₂Ca₂Cu(SO₄)₄·2H₂O, formed in arid climates, as is the case with this specimen from the type locality of Chuquicamata mine in Chile. This specimen shows various greenish areas of this mineral. The specimen was collected by mineral dealer G. Farber in 1988, and later acquired from David Shannon by Catalan collector E. Nicolau.

Reserved

This mineral species was first identified in Bergen Hill, New Jersey (USA). Stevensite is a rare phyllosilicate of the smectite group, with the formula (Ca,Na)xMg₃-x(Si₄O₁₀)(OH)₂. With black todorokite. This is an early specimen from Långban, Sweden. A systematic curiosity acquired from Shannon by E. Nicolau (Barcelona).

Reserved

Rich clusters of sharp schwartzembergite orange lenticular crystals. It is a very rare lead cloroiodate, Pb₅H₂(IO₂)O₄Cl₃. Under magnification we can see some percylite bluish aggregates. It is one of the specimens those remembered Dr. Joan Viñals (1951-2013) brought and studied from his trip to Chile in beginning of 2000's. This specimen comes from the E. Nicolau collection (Barcelona).

Reserved

In this specimen, we can see numerous tabular ferberite crystals with a very unusual orientated parallel growth. Very lustrous and intensely black in color, they are arranged on a matrix of clear quartz crystals. This specimen comes from the Nicolau collection (Barcelona) and was acquired from Dr. Joan Viñals.

85 €

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This specimen of menilite opal is very characteristic of this Granada locality. We can see different rounded figures, dolls, or ninots (in Catalan), which have adhered to each other to form a single piece. A curiosity of Spanish mineralogy.

This specimen of menilite opal is very characteristic of this Granada locality. We can see different rounded figures, dolls, or ninots (in Catalan), which have adhered to each other to form a single piece. A curiosity of Spanish mineralogy.

This specimen shows numerous lustrous, parallel-growing cylindrite crystals (Pb₃Sn₄FeSb₂S₁₄). It is accompanied by lighter gray acicular of incaite, a tin-rich Sn(II) franckeite variety (Pb,Ag)₄Sn₄FeSb₂S₁₅, which grow interlaced in the cylindrite. It is from the type locality for both species.