Uranates – Uranite, Composition, Crystallization & Structure

Uranite, Pitch Blende
Composition. An uncertain combination of the oxides of uranium, UO₃andUO₂. With small amounts of lead and the rare elements, thorium, yttrum, cerium, nitrogen, helium, argon, radium. It is the mineral in which the gas helium was first discovered on the earth, having been previously noted in the gases surrounding the sunby means of the sun´s spectrum. In it, also, was firs discovered the rare and strange substance, radium.

Crystallization. Isometric. In octahedrons, also with dodecahedrons. Less often showing cube faces. Crystals rare.

Structure. Usually massive and botrioidal; also in grains.

Physical Properties. H. = 5.5. G. = 9-9.7 (unusually high). Luster submetallic to pitchlike, dull. Color black. Streak brownish black.

Tests. Infusible. Imparts to the salt of phosphorus bead in O. F. A yellowish green and in R. F. a green color. Soluble in dilute sulfuric acid with the slight evolution of helium gas. Characterized chiefly by its pitchy luster, its high specific gravity, its color and streak.

Occurrence. Occurs either as a primary constituent of granite rocks or as a secondary mineral with ores of silver, lead, copper, etc. Found under the latter condition at Johanngeorgenstadt, Marienberg and Schneeberg in Saxony, at Joachimsthal and Priban in Bohemia, and Rezbánya in Rumania. Occur in Norway. In the United States found in isolated crystals in pegmatite veins at Middletown, Glaastonbury and Branchville, Connecticut. In the mica mines of Mitchell County, North Carolina. A narrow vein of it has been mined near Central City, Colorado.

Use. The chief interest in the minerals lies in the fact that it is the principal source of radium. This element exists in it in extremely small percentages and it is necessary to subject a large amount of the mineral to a chemical concentration in order to produces a few grains of a radium salt. Uranium, it self, has only a limited use. Experiments have been made looking toward its use in steel. In the form of various compounds it has a limited use in coloring glass and porcelain, in photography and a chemical reagents.