Zé Pinto claim, Aldeia, Cuparaque, Minas Gerais, Brazili

Regional Level Types
Zé Pinto claim	Claim
Aldeia	District
Cuparaque	Municipality
Minas Gerais	State
Brazil	Country

It is a pegmatite outcropping in a ravine on the Western slope of a hill overhanging the buildings of the Fazenda Santa Elisa, 43 kilometers ENE of Conselheiro Pena, seat of the municipe to which it belongs and from where access is easy. Coordinates: x = 282 y = 7894.2 Conselheiro Pena map. The surrounding area is made of round hills covered with grass, overhung by high sparse sugar loafs. The rare outcrops are phacoidal gneisses rich in garnet which belong to the Middle Precambrian of the Brazilian basement, dated 2,500 - 1,800 Ma. In 1989, after stripping of the soil and the thin, kaolinized rock, underground mining works began at 380 meters of altitude through a 15-meters long adit, with irregular widenings in chambers and sumps. After being abandoned for a short while, the works began again in quarry (1992), East of the old adit. The N 40°E pegmatite with a 30°NW dip is zoned, has a core with giant quartz and potassium feldspar crystals, surrounded by a coarse-grained strip, with schorl crystals, large biotite lamina and rounded nodules containing primary apatite. Are irregularly dispersed in potassium feldspar: smoky and rose quartz (massive), garnet (n = 1.828) in irregular nodules reaching 25 centimeters in diameter, flattened crystals of niobo-tantalite, light grey to bluish green chrysoberyl (d = 3.64) in multicentimetric crystals, greyish stony beryl, zircon in multi-millimetric bi-pyramidal beige prisms and massive pyrite nodules reaching 20 centimeters in diameter. Ixiolite in very fine needles and brown rosettes fills the cracks of a late apatite. Nontronite is associated to it, as well as secondary minerals of uranium, which are not specifically identified, and a few large pseudomorphe crystals of a carbonate by goethite. A few long and very blue flakes of kyanite were observed, embedded in feldspar, in the dumps of this zone. Variably flattened druses, of different sizes, the largest of which can measure two meters, are scattered in the coarse grain zone, around the core. Frequently linked to fractures having the same orientation as the pegmatite, but with a 50°NW dip, these druses, which are related to albitic substitution bodies posterior to the formation of the coarse-grained zone, are lined with slightly corroded quartz and potassium feldspar crystals, albite, muscovite and crystallized green apatite, which made the deposit famous. Four generations of apatite were identified and were the subject of a detailed study which showed it was possible for crystals of very different sizes and colors to coexist within a single pegmatitic body (Cassedanne et al., 1995).

Green apatite belonging to the second generation is always remarkably well crystallized and has made the deposit famous among mineral collectors (Cassedanne and Alves, 1990). The most common shape of the crystals is a hexagonal prism terminating in a pinacoid (0001), with vertical edges and/or bases sometimes bevelled by a second hexagonal prism and/or a hexagonal pyramid. The prisms, which are isolated or in groups of crystals without a determined orientation, irregularly interpenetrate, are a few centimeters long and have a diameter of 1 to 3 centimeters; larger specimens being rare. The crystals, which are more or less dark green, translucent to sub-opaque, are sometimes cavernous, resulting from the coalescence of small prisms with parallel axes, or they are zoned by strips of feldspar, along the c axis. Sometimes a light blue to blue green late cortex envelops certain crystals. Muscovite, albite and quartz are sprinkled over green apatite, often partially included in potassium feldspar or stuck onto mica plates surrounding the nodules that contain primary apatite. The luster of green apatite is greasy to vitreous, sometimes shiny. The measured density is of 3.21 ± 0.02. There are no cuttable crystals, all being internally fractured, with biphasic inclusions and metal plates. Over 100 kilograms of crystals were collected in the main druse, a good part of which was featured at the Tuscon Show in 1990.