簡介:"自然金為黃金的主要來源,它具有極佳的延展性,是熱和電的良好導體,同時對鏽蝕和其它化學變化的抵抗力極強,不氧化,也不容易失去光澤,因而廣泛被應用在貨幣、首飾、電鍍等方面。 金可說是一種稀有的元素,但在自然界的分佈卻相當廣泛,只是含量極微。在自然狀態產出的金,常含有銀,偶而也含有少量的銅、鉍、鉛、錫、鋅等類的金屬。 含金的熱液礦脈多數為石英脈,部分自然金也集中在石英安山岩、花崗岩、結晶片岩、砂岩或礫岩之中。台北金瓜石的金銅礦床屬於淺溫熱液的一種,過去黃金產量高居遠東之冠,為世界重要產金礦區之一。 含金礦脈或礦體受到風化崩解而成砂礫後,便被雨水沖刷至河床裡,因金的比重大,常在河流轉彎等流速減緩處堆積,日積月累,逐漸富集,從而形成砂積礦床(Placer desposits) 。台北基隆河和花蓮立霧溪過去都有人們掏洗沙金。礦物自然元素自然金 Native GoldNative gold is the major source of gold we use and it has good ductility and conductivity of heat and electricity. At the same time, it is resistant to chemical reaction and tarnish. The luster remains. It is widely used in coin making, ornaments, and electroplating. Native gold is a precious element, but the small quantity is widely distributed in nature. The occurrence of gold often associates with the small amount of copper, bismuth, lead, tin, and zinc. Hydrothermal veins with gold are the quartz deposit. Gold is often found with dacite, granite, crystalline schist ,sandstone or Breccia. Gold-copper deposit of Chin-Kua-Shih, Taipei falls into the category of mild growing hydrothermal veins; in the past, it had the largest production in the Far East area and one of the important gold mining areas. Gold deposit or minerals after weathering is likely to be disintegrated into sand and washed down to the river bed. Because of high specific gravity, gold is accumulated as placer deposits. Gold washing used to be found in Keelung River in Taipei and Liwu River in Hualien. "