FMF - Foro de Mineralogía Formativa

[yowanni]

El cuarzo es una preciosidad, y la geoda debió de ser una maravilla (por cierto, 50000 ejemplares, que barbaridad)

[Jmiguel]

Hola Yowanni. Sí aquello debió ser impresionante. He encontrado una información más completa sobre el descubrimiento:
In 1966 a spectacular quartz crystal pocket was discovered in this mine (von Bezing and Kotze, 1993). Before this, the mine had been rather unremarkable as far as specimen production was concerned. This find remains unique in the district. While tunneling away from the shaft on the 88-meter level, in a southerly direction, one of the miners, a Mr. Kennedy, noticed an area of decomposed rock on the sidewall of the drift. While testing for stability with a crowbar, he broke into a chamber measuring 12 × 12 meters across and some 6 meters high. The floor, walls and roof were covered by thousands of quartz crystals of all sizes. Most of the larger crystals were lying on the floor, partially embedded in a layer of green chlorite 15 cm thick. Smaller second-generation clusters were coating the sidewalls and most of the crystal fragments.

A conservative estimate is that about 50,000 single crystals and clusters amounting to several metric tonnes were removed. The largest crystals measure 180 cm and weigh some 250 kg. Most major private and public collections in South Africa now have examples, and many specimens have reached Europe and the United States. Large crystals have also been used as gate posts in front of a local hotel, others as decorations on graves! The crystals are generally colorless to smoky, with green chlorite preferentially coating only some faces, dulling the luster slightly. On the chloritecoated faces of most of the crystals and fragments, gray calcite (rounded scalenohedrons) and small (up to 1 cm) prismatic, yellow barite crystals are found: this combination makes specimens from the Jan Coetzee pocket easily identifiable. Minute crystals of chalcopyrite are also common, and these may reach 1 cm in size. Most of the larger quartz crystals are tapering prisms with evidence of basal tectonic fracture and rehealing, resulting in pseudo-doubly terminated crystals. Many of the second-generation quartz crystals are complex and distorted. Calcite, massive and in crystals, was also found.

[Jmiguel]

Cuarzo Cetro Amatista y Ahumado. Goboboseb. Namibia.

[Jmiguel]

Cuarzo gwindel. Glacier d´Argentiere in Chamonix.
Inclusiones de clorita.

[Jmiguel]

Cuarzo amatista con hematites. Orange River. Namibia.

[Jmiguel]

Cuarzo ahumado Gwindel.
Goeschener Alp
Uri
Suiza

[Jmiguel]

Cuarzo. Jinlong. Guandong. China. 2006.

[Jmiguel]

Cuarzo Jacaré. Minas Geraes. Brasil.

[Jmiguel]

Cuarzo citrino. Minas Geraes. Brasil.

[Jmiguel]

Cuarzo cetro amatista. Goboboseb. Namibia.

[Jmiguel]

Amatista. Khomas Hochland. Namibia.

[Jmiguel]

Cuarzo citrino. Minas Geraes. Brasil.

[Jmiguel]

Continúo la exploración sobre la transparencia en los cuarzos iniciada e mi historia sobre el arco iris en:
https://www.foro-minerales.com/forum/viewtopic.php?t=1569

[Jmiguel]

Gran transparencia y brillo, así como forma estilizada, para este cuarzo de Diamantina

[Jmiguel]

Cuarzo de diamantina, con excepcional brillo, y transparencia en la parte superior.

[Jmiguel]

Cuarzo catedral. Minas Geraes. Brasil.

[Jmiguel]

Cuarzo con Albita. Lavra do Sapo, Conselheiro Pena. Minas Geraes. Brasil

[Jmiguel]

Cuarzo, Diamantina, Minas Geraes. Brasil

[Jmiguel]

Transparencia de un cuarzo con inclusiones. Curvelho. Minas Geraes. Brasil

[Jmiguel]

Cuarzo citrino doble terminado. Minas Geraes. Brasil