Brass at Warmley. By the mid-to-late 18th century developments in cheaper zinc distillation such as John-Jaques Dony's horizontal furnaces in Belgium and the reduction of tariffs on zinc as well as demand for corrosion-resistant high zinc alloys increased the popularity of speltering and as a result cementation was largely abandoned by the mid-19th century. Brass Brass is an alloy of copper and zinc, in proportions which can be varied to achieve varying mechanical and electrical properties. It is a substitutional alloy: atoms of the two constituents may replace each other within the same crystal structure. In contrast, bronze is an alloy
Rare-earth element rocks containing rare-earth metals exist in Helmand province near the village of Khanneshin. The USGS study team has located a sizable area of rocks in the center of an extinct volcano containing light rare-earth elements including cerium and neodymium. It has mapped 1.3 million metric tons of desirable rock, or about 10 years of supply at current demand levels. The Pentagon has estimated its value at about $7.4 billion. Rare-earth element A rare-earth element (REE) or rare-earth metal (REM), as defined by IUPAC, is one of a set of seventeen chemical elements in the periodic table, specifically the fifteen lanthanides,