Gold belonged to the precious metal because it is resistant to rust and do not react with acids. Gold is used to make a variety of jewelry, such as rings, necklaces, bracelets, earrings, trophy and crown. Gold mine located in Cikotok (West Java) and Rejang Lebong (Bengkulu). Gold content is expressed in carats. Grade 24-karat pure gold (100%). For gold jewelry made other metals should be mixed. 22 carat gold having a purity of 22/24 x 100% = 91.66%, meaning that 91.66% is gold and 8.34% is other metals. 23 carat gold having a purity of 23/24 x 100% = 95.83%, meaning that 95.83% is gold and 4.17% is other metals.
Silver are produced from Yogyakarta and Kendari. Items made of silver, for example ashtrays, Robyong lamp, vase, bowl, plate and so on.
Tin ore is produced on the island of Bangka, Belitung, and Singkep. Tin smelting contained in Muntok. Tin is used for brazing, making craft items, as well as to coat the cans so as not to rust.
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