Tabataud Quarry

45.5250.67527777777778Koordinaten: 45 ° 31 '30 " N, 0 ° 40' 31" E

The Tabataud quarry is an interesting mineral archaeological site in the north-western Massif Central of France. Once granodiorite was mined in him. Among mineral collectors, he has become known as good archaeological site.

Geography

The Tabataud quarry (sometimes written Tabateaud ) is just 1 kilometer southeast of the city center Nontrons, on the left side of the valley of the Bandiat to around 165 meters. To him the D 707 of Nontron to Saint -Pardoux- la -Rivière passes. For the actual Quarry also still has two other smaller quarries in the immediate neighborhood, the Maspeyrot - Lagarde- quarry and the Moulin Blanc quarry, both of which are, however, of older date. All these now disused quarries can be reached from the D 707. Your entry is not dangerous because of falling rocks and imminent danger of collapse.

Geology

The Tabataud quarry and the other two quarries are in Piégut -Pluviers granodiorite, in which fine-grained, dark, biotite - and amphibole - leading Marginal Facies. Because of its slight bluish color of this rock is called locally as granite bleu ( blue granite ). The extreme west of the quarry runs through a NNE -SSW - striking fault zone that separates the granodiorite compared to the plagioclase -bearing paragneisses. The granodiorite is in the quarry area traversed by a mineralized corridor floor, which generally northwest-southeast - trending veins consists of 17 relatively thin ( 1-3 cm width). The at Moulin Blanc pending and only briefly degraded Puyssechet -speed sweeps east-west and reaches at least 30 centimeters from strength to strength. In addition to the veins occur in the quarry on smaller Pegmatitgänge.

Mineralogy

The aisles are among the typical sphalerite - pyrite - galena - chalcopyrite mineralization, with the galena occurs clearly here in the foreground. It is hydrothermal mineralization of the middle temperature range (300 to 150 ° C), very similar to Cantonnier gear. In Tabataud quarry but the main focus is on the primary galena and not on the secondary minerals.

Gangue minerals in the veins are quartz and / or barite. On ordinary minerals also occur added calcite and dolomite. Secondary minerals are the lead minerals anglesite, cerussite, pyromorphite and Wulfenite and the iron sulfides pyrite and marcasite. As a rarity occurs the Bituminous pseudo mineral ozokerite.

The Pegmatitgänge perform beautifully designed, 2 -millimeter grenade and tourmalines ( here: schorl ) in the millimeter range and up to 5 mm reach, asparagus green apatites.

The Erzgangminerale in detail:

• Anglesite (Pb [ SO4 ] ): rare; millimeter-sized, colorless prisms.
• Barite (Ba [ SO4 ] ): common; gait; bladed habit; white documents, spherical ball, usually together with galena ( and marcasite ) occurring.
• Galena ( galena ) (PbS ): very common; Crystal size up to several centimeters; usually be sensed in the state ( iron oxide coating ), often dull ( oxidation), occasionally in Zerrklüften but extremely brilliant, excellent quality; Cube and octahedron; on quartz, sometimes on calcite, dolomite or barite growing up; overgrown by cerussite, pyrite, marcasite, quartz and ozokerite.
• Cerussite (Pb [ CO3 ] ): local frequently occurring; crystallized on galena as its transformation product; forms decimeter -sized coatings with crystals in the millimeter, rarely also in the centimeter range; a crossed habit, prisms, primarily to the a-axis, sometimes stretched after the c-axis crystals; White single crystals and twins.
• Dolomite ( CaMg [ CO3 ] 2): relatively rare; associated with galena; Millimeter, pink rhombohedral, sometimes in saddle-shaped habit.
• Calcite (Ca [ CO3 ] ): frequent late-stage Zerrspalten; associated with galena; peak ( reflecting) and flat (matte ) rhombohedron; milky single crystals can be up to 5.5 inches tall.
• Gypsum ( Ca [ SO4 ] • 2H2O)
• Marcasite ( FeS2 ): very common low-temperature mineral; very susceptible to weathering; overgrows the galena, often in beautiful, well-shaped single crystals in the millimeter range; up to square decimeter large crusting; Hahnenkamm habit; Twinning by (110).
• Ozokerit (or smelling wax): associated with quartz and galena; to 0.09 mm wide, brown globules of bitumen ( mixture of volatile and solid hydrocarbons of the methane series ).
• Pyrite ( FeS2 ): relatively rare; spherical crystal aggregates of millimeter-sized single crystals of quartz, sometimes on dolomite.
• Pyromorphit ( Pb5 [Cl | ( PO4 ) 3] ): common; However beautiful crystals are rare; Crusts on strong angegriffenem galena; occasionally the galena disappears totally, the Pyromorphit then assumes Boxwork habit; pale yellow to deep green crystals; bright green, needle-shaped pyromorphite sometimes grows in very heavily modified columns nests in the granodiorite.
• Quartz ( SiO2): frequent gait; very beautiful, 5-8 mm large single crystals ( with double extension) on galena; can in turn be covered by a thin skin of green pyromorphite and additionally carry microcrystals of Wulfenite; otherwise mostly classical habit with poorly developed prisms, colorless to milky; also slightly smoky, amethystartige individuals occur.
• Sphalerite (ZnS ): not very often; Microcrystals, which are associated with galena.
• Wulfenite (Pb [ MoO4 ] ): very rare; sitting on matt green pyromorphite; orange, tabular, 2 to 3 millimeters, very rarely 1 cm large single crystals; originated near the surface; the molybdenum is expected to come from the molybdenite in the granodiorite very finely divided.

History

Work on Tabataud quarry began in the 1890s. The resulting reduction in the ore was earned though it was not in the forefront of the mining activities. The granodiorite was initially rather a sought-after building and paving stone, and later the rock was crushed mainly to gravel and granules. In 2003, the work was finally stopped at the quarry since the quarry is used as storage space for the countless, from hurricane Lothar in 1999 uprooted around tree trunks.

Importance

The Tabataud quarry would probably contain the most beautiful galena crystals France. He also represents one of the very rare sites of France for Wulfenite and also leads the rarity ozokerite. The Cerussite is of exceptional quality and rich variety of shapes.

The numerous pegmatites, veins and Zerrspalten point to a tectonically induced expansion phase in the granodiorite out, which takes place after cooling it needs to be and allowed the mineral- laden pneumatolytic and hydrothermal solutions, the entrained metals ( especially lead ) deposit, the higher tempered Pegmatitstadium likely to be older. A radiometric age study at galena with the uranium-lead method yielded a unterpermisches age of 300 million to 250 million years BP for the mineralization. The spatial orientation of the courses can be aligned on a SE-NW, close under transtension occurring, dextral shear.