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Steatite of  Meleto quarry

Steatite of Meleto quarry

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The  “Scaly-Clays Complex”  is the prevailing  rock formation  in the section of the Appennines between Emilia and Tuscany, but many different kinds of alloctonous rocks may be observed there; ophiolites are frequent and, among them, the so-ca/led “Green Rocks”  (gabbros, diabases, serpentinites).  They are chaotically and accidentally embedded in the clastic sedimentary clays; probably  originated  by intensive submarine  volcanic  activity between Corsica and Tuscany, they were fragmented   and moved along the Appennines by orogeny between Cretaceous and Pliocene.  Ophiolitic outcroppings  are well known  in Tuscany in the Rognosi Mts, Val di Cecina, Livornesi Mts, Serchio Valley and in the area of Monte Ferrato/Impruneta  near Florence . The Meleto quarry (also said Palagio quarry), where the special  clay far   the famous   “Cotto Fiorentino”  floor-tiles is exploited,  is located near Impruneta; grey-green  hydrothermalites (serpentinites,  carbonates, quartz)  outcrop there, frequently crossed by calcite veins with interesting mineralizations  including  Ni-minerals.

MINERALS

Most of the minerals found in the quarry occur as well cristallized micro specimens so they are hereafter described with reference to their matrix rocks; it is impossible to locate the various occurrences within the quarry, due to continuous and active exploiting.

MINERALS IN SERPENTINITES.

Talc (“Steatite “): Within the rare masses of serpentine there are calcite veins inside which there are aesthetic aggregate mammillary of steatite. Perhaps the most aesthetic specimens at European level. As out standing , bright-green specimens. It occurs as either mammillary or globular aggregates to even 2 cm in diameter, grouped to cover large surfaces. Usually fluorescent in yellow.

MINERALS IN CARBONATIC VEINS AND HYDROTHERMALITES.

  • Calcite: in cavities as beautiful rhombohedral , milky to clear xls to 6 mm, in para/lei growths.
  • Celestite: as tabular single xls to some mm, pale sky-blue, transparent to translucent.
  • Dolomite: as cream-white micro rhombohedrons.
  • Goethite: as micro dull -black octahedrons, pseudo after pyrite .
  • Hematite: as lustrous micro blades, sometimes grouped in rosettes.
  • Jamborite: as either pseudos  after millerite or as pale-green crusts and masses; with millerite and black micro octahedrons ( vaesite?).
  • Marcasite: as micro globular, blackish aggregates.
  • Millerite: as nice brass-yellow needles to 5 mm, grouped as either stars or sprays or urchins; with pyrite, jamborite, vaesite (?).
  • Pyrite, as micro xls of many different forms.
  • Quartz, as prismatic, some times lattened, milky-white to clear xls; also in parallel growths . Often supporting other minerals.
  • Sphalerite: as micro tetrahedrons, honey -yellow to yellowish­ orange.
  • Vaesite (?): lustrous black micro octahedrons have been tentatively identified as vaesite due to sharp cleavage surfaces and close association with millerite and jamborite.
  • Sky-blue unknown: as felts of micro needles.
  • Orange-red unknown (reevesite?): as micro prisms .

MINERALS IN HYDROTHERMALITES.

  • Anatase: as micro tabular, honey-yellow xls.
  • Barite: as white tabular xls to l cm in rare cavities.
  • Hematite: as metallic grains.
  • Quartz: as bipyramidal, compenetrated xls, embedded  in rock .

MINERALS IN SCALY CLAYS.

  • Barite: as short tabular, colorless to pale-blue  xls to l cm.
  • Calcite: as short prismatic,  lenticular or scalenohedral xls to 3 cm; colorless to white, sometimes as nice, complex specimens.
  • Chacopyrite:  found  only once as crude tetrahedrons.
  • Celestite: rare in this association. One beautiful blue xl reported from the early works.
  • Fluorite: rare, as micro colorless xls.
  • Pyrolusite: as dendrites an calcite.
  • Pyrrhotite: as thin tabular, hexagonal xls to 8 mm; rarely as rosettes.

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