It is likely to occur wherever galena is found, as a secondary mineral derived from the galena. In this country it is not used as an ore, for, as in the Leadville district, veins which have cerrusite near the surface change at moderate depths, and galena takes the place of the cerrusite. It is found all down the Appalachian Mountains, and in all the Cordilleran States. Especially fine specimens have come from the Cœur d’Alene district in Idaho. Anglesite PbSO₄ Pl. 18 Occurs in grains and masses, or in tabular and prismatic orthorhombic crystals; hardness 3; specific gravity 6.3; colorless; luster adamantine; transparent on thin edges. Two modes of occurrence are characteristic, one in cavities in galena, the other in concentric layers around a nucleus of galena. In the former case fine crystals are developed, in the latter the mineral is in masses. The crystals look like those of barite, but are soluble in nitric acid while the barite is insoluble. Sometimes the crystals are prismatic with pyramidal faces instead of the tabular form. It is found in the lead mines associated with galena, and in this country is not used as an ore for lead, but in Mexico and Australia it is abundant enough to be mined as an ore. Exposed to water which has carbon dioxide in it, and most surface waters have some, it readily changes to cerrusite. It is found in Missouri, Wisconsin, Kansas, Colorado, and Mexico. Pyromorphite Pb₅Cl(PO₄)₃ Pl. 17 _Green lead ore_ Occurs in small barrel-shaped hexagonal crystals, and in fibrous or earthly masses; hardness 3.5; specific gravity 7; color green to brown; luster resinous; translucent on thin edges. Pyromorphite is found in the upper levels of lead mines, and is formed by the decomposition of galena. Its green color (sometimes shading off toward brown), considerable weight and resinous luster, serve to distinguish this mineral. The crystal form is that of a simple hexagonal prism, with the ends truncated. It is found in Phœnixville, Penn., Missouri, Wisconsin, Colorado, New Mexico, etc. The Zinc Group Zinc and copper made the brass of early Roman times; but even then, zinc was not known as a separate metal, the brass being made by smelting rocks in which both zinc and copper occurred, the zinc never being isolated until much later. Some time in the later Roman times it seems to have been obtained separately, but then and all down through the Middle Ages zinc and bismuth were confused. Our earliest record of zinc being smelted, as we know it today, was about 1730 in England. In those earlier days, the product, zinc, or bismuth, or both together, were known as “spelter,” and this name has clung to zinc in mining and commercial circles; so that today, if one looks for quotations in the newspaper, he often finds zinc under the head of spelter.