Search Results (2)

Hydrothermal scheelite from three Romanian occurrences was analyzed in order to ascertain its structural, physical, vibrational, paragenetic, and crystal-chemical peculiarities as an important tool for characterizing the metallogenetic behavior and facilitating the ore-processing. All three occurrences, i.e., Ciclova and Oravița in Banat and Băița Bihor in the Bihor Mountains, are related to skarn deposits developed at the contact of Upper Cretaceous granodioritic bodies with Mesozoic calcareous deposits. Typical crystals show {001}, {111}, and {101} forms and are up to 15 mm across. The structure was successfully refined as tetragonal, space group I4₁/a, with R₁ = 0.0165 (Ciclova), 0.0204 (Oravița), and 0.0237 (Băița Bihor), respectively. The cell parameters refined for the same samples are a = 5.2459(10) Å and c = 11.3777(5) Å at Ciclova, a = 5.2380(2) Å and c = 11.3679(8) Å at Oravița, and a = 5.2409(2) Å and c = 11.3705(6) Å at Băița Bihor. The multiplicity of bands in both infrared absorption and Raman spectra is consistent with the S₄ punctual symmetry of the tungstate anion, agreeing with the structural data. In all cases, the analyzed scheelite is close to the CaWO₄ end-member. Cathodoluminescence peculiarities at the level of single crystals suggest that they crystallized in a slightly oxidizing to reducing environment from late hydrothermal solutions. Textural and paragenetic peculiarities suggest that scheelite from the three occurrences crystallized from epithermal, low-temperature, fluoride- and boron-bearing aqueous solutions. Full article

The Antoniu, Antoniu North, and Blidar Contact orebodies from the Băița-Bihor skarn deposit, Romania have been investigated using optical and electron microscopy. Electron probe microanalyses were acquired on samples from the Blidar Contact orebody. Bornite is the most abundant Cu-sulfide and hosts native bismuth, joséite-B, emplectite, and wittichenite. Kësterite and ferrokësterite were identified for the first time in the Băița-Bihor deposit; the occurrence of stannite was also confirmed. Temperatures of ore deposition in the Blidar Contact orebody are constrained from the compositions of sphalerite-kësterite and sphalerite-ferrokësterite pairs at 287 ± 25 °C to 310 ± 35 °C, and 447 ± 17 °C to 503 ± 68 °C, respectively. Full article