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RM1615   Cassiterite on Quartz

Viloco Mine, Loayza, La Paz, Bolivia

Group of cassiterite crystals, very sharp, with defined faces and edges, good brilliance and transparence showing toasted honey lights. They show very clear cyclic twins. They are disposed very aerial and aesthetically contrasting on a matrix of quartz crystals with arsenopyrite. From a classic locality.


Size: 7.0 x 5.3 x 4.0 cm.
Main crystal: 18 x 15 mm.
Found in 2016

 

RM1614   Cassiterite on Quartz

Viloco Mine, Loayza, La Paz, Bolivia

Group of cassiterite crystals, very sharp, with defined faces and edges, good brilliance and transparence showing toasted honey lights. They show very clear cyclic twins. They are disposed very aesthetically contrasting on a matrix of quartz crystals. From a classic locality.


Size: 6.5 x 5.3 x 3.0 cm.
Main crystal: 14 x 12 mm.
Found in 2016

Price: 80 €Reserved
 

RM1617   Cassiterite on Quartz

Viloco Mine, Loayza, La Paz, Bolivia

Group of cassiterite crystals, very sharp, with defined faces and edges, good brilliance and transparence showing toasted honey lights. They show very clear cyclic twins. They are disposed very aesthetically contrasting on a matrix of quartz crystals with arsenopyrite. From a classic locality.


Size: 4.8 x 4.5 x 3.5 cm.
Main crystal: 15 x 15 mm.
Found in 2016

Price: 80 €Buy
 

RM1248   Galena with dolomite

Sayari Mine, Cerro Sayari, Arque, Cochabamba, Bolivia

These specimens of Bolivian galena are unusual in collections. These mines on Cerro Sayari (4,300 meters elevation) were mined for silver during the colonial times. In this sample we would like to emphisize a group of sharp galena crystals, with metallic luster and polysynthetic growths, showing cube faces and minor facets of the octahedron. Aesthetic piece and very rare on the market.


Size: 8.4 x 6.4 x 4.7 cm.
Main crystal: 21 x 20 mm.
Found in 2015.

 

RM785   Native bismuth

Viloque river, La Paz, Bolivia

These rounded nuggests are found nowadays in the bed of the river Viloque. They have been teared off from the mineralized veins by the glacial erosion and actually are found in gold placers. This piece is a classic example of these nuggets, intense silvery metallic luster, rounded by abrasion, and a good size for this locality. Native bismuth is known from many localities worldwide, but nuggets from Viloque River are the mostn known for the species.

 


Size: 1,9 x 1,4 x 1,3 cm. (10 g.)

 

RM652   Native copper

San Agustín Mine, Corocoro, Pacajes, La Paz, Bolivia

A very aesthetic copper specimen formed by laminar to arborescent forms, with rounded crystals and very aerial disposed. The color is natural, withouth chemical treatments, and it shows some luster. It comes from Bolivian mine, near CoroCoro, famous for pseudomorphs of native copper after hexagonal cyclic twins of aragonite, but these laminar shape is uncommon for locality.


Size: 6,5 x 5,1 x 4,4 cm.
Found in 2012.

 

RM1122   Sphalerite pseudom. after wurtzite

San José mine, Ciudad de Oruro, Cercado, Oruro, Bolivia

A huge size group of interpenetrated crystals of hexagonal shape, with a dark gray metallic color and brilliant luster. Crystals of this specimen remind wurtzite for its complex hexagonal shape and dipyramids observed. Many similar samples from this mine has been classified as wurtzite. For this reason we heve proceeded to analyze them. The results indicate that this is a really amazing and interesting pseudomorphosis of sphalerite after wurtzite. A great opportunity for psedomorph and Bolivian mineral collectors.

Studies were carried on by X-ray diffraction of the matrix and hexagonal crystals. They have shown that it is sphalerite. Also, the Raman spectra shows that in the innermost areas of the crystals wurtzite presence has been detected, the rest is sphalerite. SEM-EDS yield a composition:  (Zn1.05,Fe0.09)Σ=1.14S1.00.

Specimens of well developed wurtzite are unusual. This hexagonal zinc sulphide, with some iron, presents dimorphism with sphalerite. It is known that wurtzite is stable at high temperatures, low temperatures being the most stable phase sphalerite. This Bolivian mine is the type locality for the wurtzite. We will send the analysis reports to the specimen buyer.


Size: 9.6 x 8.9 x 4.8 cm.
Main crystal: 28 x 25 mm.

Analyzed specimen with report
 

RM1962   Sphalerite pseudom. after wurtzite

San José mine, Ciudad de Oruro, Cercado, Oruro, Bolivia

A huge size group of interpenetrated crystals of hexagonal shape, with a dark gray metallic color and brilliant luster. Crystals of this specimen remind wurtzite for its complex hexagonal shape and dipyramids observed. Many similar samples from this mine has been classified as wurtzite. For this reason we heve proceeded to analyze them. The results indicate that this is a really amazing and interesting pseudomorphosis of sphalerite after wurtzite. A great opportunity for psedomorph and Bolivian mineral collectors.
Studies were carried on by X-ray diffraction of the matrix and hexagonal crystals. They have shown that it is sphalerite. Also, the Raman spectra shows that in the innermost areas of the crystals wurtzite presence has been detected, the rest is sphalerite. SEM-EDS yield a composition:  (Zn1.05,Fe0.09)Σ=1.14S1.00.
Specimens of well developed wurtzite are unusual. This hexagonal zinc sulphide, with some iron, presents dimorphism with sphalerite. It is known that wurtzite is stable at high temperatures, low temperatures being the most stable phase sphalerite. This Bolivian mine is the type locality for the wurtzite. We will send the analysis reports to the specimen buyer.


Size: 5.7 x 4.2 x 3 cm.
Main crystal: 15 mm.

Analyzed specimen with report


 

RM1124   Sphalerite pseudom. after wurtzite, with plumbogummite and franckeite

San José mine, Ciudad de Oruro, Cercado, Oruro, Bolivia

Group of interpenetrated crystals of hexagonal shape, with a dark gray metallic color and brilliant luster. Crystals of this specimen remind wurtzite for its hexagonal shape and dipyramids observed. Many similar samples from this mine has been classified as wurtzite. For this reason we heve proceeded to analyze them. The results indicate that this is a really amazing and interesting pseudomorphosis of sphalerite after wurtzite. Accompanied by nice brilliant franckeite globular crystal aggregates and small hexagonal prism of plumbogummite (also a pseudomorph). A great opportunity for psedomorph and Bolivian mineral collectors.

Studies were carried on by X-ray diffraction of the matrix and hexagonal crystals. They have shown that it is sphalerite. Also, the Raman spectra shows that in the innermost areas of the crystals wurtzite presence has been detected, the rest is sphalerite. SEM-EDS yield a composition:  (Zn1.05,Fe0.09)Σ=1.14S1.00.

Specimens of well developed wurtzite are unusual. This hexagonal zinc sulphide, with some iron, presents dimorphism with sphalerite. It is known that wurtzite is stable at high temperatures, low temperatures being the most stable phase sphalerite. This Bolivian mine is the type locality for the wurtzite. We will send the analysis reports to the specimen buyer.


Size: 7.3 x 5.2 x 3.6 cm.
Main crystal: 18 x 16 mm.

Analyzed specimen with report
 

RM929   Franckeite with jamesonite and stannite

Itos Mine, Ciudad de Oruro, Cercado, Oruro, Bolivia

A very rich specimen of this rare sulphosalt showing brilliant and sharp franckeite lanceolate crystals forming globular aggregates. They are accompanied by delicate and shiny needles of jamesonite and idiomorphic crystals stannite with a brown color and dull. This combination makes these samples pieces very interesting for systematic mineral collectors. We have analized each species and we will send analysis to the buyer.

Specimens from this mine are hard to distinguish from those of the neighboring San Jose mine and, since the administrative office for both mines was at San Jose, most Itos mine specimens in foreign collections ended up labelled "San Jose mine".


Size: 5,0 x 4,5 x 3.0 cm.
Main crystal: 4 x 3 mm. stannite

Mineral analizado / Analyzed species.
 

RM1036   Magnetite

San Calixto prospect, Cerro Huañaquino, Potosí, Bolivia

Rich group of octahedral magnetite crystals with a good size. Brilliant, intense gray metallic tone and disposed very aesthetically on the rocky matrix. A classic that is hard to see on the market.


Size: 12.0 x 10.4 x 4.5 cm.
Main crystal: 13 x 12 mm.
Found in 2002.

Ex-col. Joan Rosell.
Magnetic properties: It is attracted by magnets


 

RM1927   Magnetite

San Calixto prospect, Cerro Huañaquino, Potosí, Bolivia

Rich group of octahedral magnetite crystals with a good size. Brilliant, intense gray metallic tone and disposed very aesthetically on the rocky matrix. With a small ding. A classic that is hard to see on the market.


Size: 9.7 x 4 x 3.2 cm.
Main crystal: 12 x 12 mm.

Price: 65 €Buy
 

RM634   Vivianite

Canutillos Mine, Veta (vein) Tomokoni, Colavi, Cornelio Saavedra, Potosí, Bolivia

Perfection! A nice crystal of vivianite, with a deep green color and well defined. With transparence that show the green tone characteristic for the species. Very aerial disposed on a solid sandstone matrix, sulfur free which ensures the stability of the specimen in the future. It is better in live than on the photo, but enjoy them. An exceptional specimen.


Size: 6,9 x 6,5 x 4,5 cm.
Main crystal: 38 x 20 mm.

Precio reducido-Reduced price 310€
 

RM300   Silver

Estaño Orcko mine, Colavi, Machacamarca, Cornelio Saavedra, Potosí, Bolivia

Specimen of a little-known locality. These sample shows aggregates of silver crystals, with an intense luster and tones between white and golden. They are disposed on a matrix with quartz and iron oxides with which they contrast.


Size: 6.4 x 4.8 x 2 cm.
Main crystal: 8 mm.
Found in 08/2011

 

RM1270   Japan law quartz twin with cassiterite

Siglo XX mine, Llallagua, Rafael Bustillo, Potosí, Bolivia

The Siglo XX mine is one of the most impressive Bolivian mining localities. It produces some amazing specimens of common species like quartz, few of the with the Japan-Law twin which are are well known in the mineral world. In this sample we can enjoy a good sized Japan-twin quartz crystals, with transparence and luster. This nice twin is disposed on a druse of hyaline quartz crystals.
To give a unique touch to the specimen a group of cassiterite crystals with good brilliance and deep black color, very rich in faces, interpenetrating between them and with some quartz crystals. A superb specimen.


Size: 11.0 x 6.8 x 6.3 cm.
Main crystal: 25 x 15 mm. (macla/twin)

 

RM129   Sigloite pseudomorph after Paravauxite

Mina Siglo XX, Llallagua, Rafael Bustillo, Potosí, Bolivia

Group of Sigloite crystals pseudomorph after Paravauxite, partially covering the rocky matrix. Paravauxite and sigloite differ chemically by the presence of a single water molecule. Sigloite is white to yellowish. The Siglo XX Mine is the type locality for Sigloite species.


Size: 5.5 x 3.5 x 2.5 cm
Main crystal: 9 x 2 mm

Fluorescent under long wave UV
 
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