Galena diode. Making such wireless receivers was a popular home hobby in Britain and other European countries during the 1930s. Scientists associated with the investigation of the diode effect are Karl Ferdinand Braun and Jagadish Bose. In modern wireless communication systems, galena detectors have been replaced by more reliable semiconductor devices. Galena Galena, also called lead glance, is the natural mineral form of lead(II) sulfide. It is the most important ore of lead and an important source of silver. Galena is one of the most abundant and widely distributed sulfide minerals. It crystallizes in the cubic crystal system often showing octahedral
Mineral industry of Armenia precious metal mines. Among these mines, about 400 mines, including 22 base metal, non-ferrous metal and precious metal mines are currently being exploited. Among the base metal and precious metal deposits, there are 7 copper-molybdenum mines, 3 copper mines, 13 gold and gold-polymetallic mines, 2 polymetalilc mines and 2 iron ore mines. In addition to those mines registered in the state inventory of mineral resources, there are an additional 115 deposits of various deposits that have been discovered. In 2017 mining industry output with grew by 14.2% to 172 billion AMD at current prices and run at 3.1% of Armenia's