NORTHWESTERN OHIO : CALCITE , DOLOMITE AND FLUORITE 1
Calcite is by far the most abundant mineral in the Devonian rocks at Pugh Quarry. The large crystals, from 5 mm to 10-15 cm long, are predominantly brown with wide variations in hue and intensity. The small crystals, smaller than 5 mm, range from colorless to gray-yellow to pale yellow. Both large and small crystals consist almost entirely of scalenohedral forms (dog-tooth spar habit). The most common and most easily recognized type of twinning in the large crystals is on the (0001) plane. Both dolomite and fluorite are minor minerals at Pugh Quarry, although fiuorite is found in all parts of the Quarry. Dolomite crystals occur as secondary encrusting material and are most common in vugs. OHIO J. SCI. 79(1): 24, 1979 In this third paper on the mineralogy of Pugh Quarry, calcite, dolomite and fluorite are described. The quarry is located in the SW3^, SW^, Sec. 6, T.4N, R.9E in Milton Township, Wood Co., Ohio. Its sulfide mineralization, including marcasite, pyrite, and sphalerite has been previously described (Parr and Change 1977, 1978).
BLUE JOHN FLUORSPAR
Summary The paper presents an account of the mineralogy, geological occurrence and history of the blue and white banded fluorspar found near Castleton in Derbyshire. Blue John is shown to be a fluorspar, coloured by bituminous inclusions, deposited as cavity-linings and replacements in Carboniferous Limestone of reef and massif facies. Alternative hypotheses of the cause of the colouring in Blue John are discussed. Lying more or less parallel to the bedding of the limestones, the deposits are in pipe-veins rising up the flanks of a pseudo-anticlinal structure formerly covered by impervious Namurian shales, which now outcrop only round the flanks of Treak Cliff. The relationships between Blue John and the associated minerals (calcite, barytes, galena, pyrites and quartz) are described, and an account is given of the history of the use of Blue John and the methods of manufacturing ornaments. Reasons are given for the conclusion that the story of the use of Blue John by the Romans is without foundation.
Vasa Murrina again
A reassessment of the problem of Vasa Murrina based upon a study of a fluorspar vase in A. Loewental's possession was recently published in this Journal (XXXIX, 1949, 31 ff.) by Loewental and myself. The late C. E. N. Bromehead very kindly added a ‘Mineralogical Note’, afterwards elaborated in Antiquity (XXVI, 1952, 65 ff.), supporting his view that the true Murrines were fluorspar. But even by 1952 Bromehead was unable to cite any actual fluorspar vase of Roman date whose present whereabouts is known, other than the two which Loewental and I had published. He did, however, refer to Corsi's mention (1845) of ‘two antique fluorspar vases found in Rome, one in the Museo Kircheriano… another in the possession of Signor Gillet-Laumont’. This Kircheriano specimen is also mentioned by Middleton as late as 1892. Bromehead also cites independent statements by Egglestone and Sheppard that ‘Blue John’ vases had been found at Pompeii and Herculaneum respectively.