Brass Late Roman. Latten is a term for decorative borders and similar objects cut from sheet metal, whether of brass or bronze. Aquamaniles were typically made in brass in both the European and Islamic worlds. The cementation process continued to be used but literary sources from both Europe and the Islamic world seem to describe variants of a higher temperature liquid process which took place in open-topped crucibles. Islamic cementation seems to have used zinc oxide known as "tutiya" or tutty rather than zinc ores for brass-making, resulting in a metal with lower iron impurities. A number of Islamic writers and
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,