| Show 0 pitchblende the research department of the colorado school of mines at golden gives the following information regarding pitchblende pitchblende occurs afi ni fissure veins in igneous rocks like granite it is valued for its uranium and radium contents it is not found in sedimentary rocks like sandstone although alteration products of it may be found therein such alteration products are colored yellow or greenish and when in sufficient concentration and quantity are valuable for their uranium contents the radium value in these these is small as a rule pitchblende is found in in vein matter in stringers varying from knife blade t thickness to several inches it is bunchy the associated minerals in addition to vein matter are sulphides sulp hides such as zinc blende galena and iron pyrite the latter usually predominates it is detected in these streaks by the following properties color pitch black velvety black brownish sometimes with a grayish or greenish cast A streak on rough porcelain i e the edge of a broken plate is brownish black olive green or grayish luster dull metallic greasy fracture Coric hoidal that is with smooth curved surfaces to uneven brittle hardness less than quartz it is not scratched by a knife blade unless weathered specific gravity heavier than iron or steel also heavier than galena the following common minerals are likely to be mistaken for pitchblende by prospectors obsidian or volcanic glass which differs from pitchblende in its lightness glassy luster and light streak magnetite which differs from pitchblende mainly in that it is attracted by the magnet hematite which differs from pitchblende de mainly in possessing a red streak |
