Raw gold, also known as natural gold, barren gold and raw gold, is the object of mature gold, which is mined from mines or alluvial deposits at the bottom of rivers without smelting and refining. There are two kinds of raw gold: ore gold and placer gold.
Mineral gold, also known as synthetic gold, occurs in mines and gold mines. Most of them are deposited together with underground hot springs through rock cracks, and they are often caught in rock cracks. After mining, crushing and elutriation, large gold can be directly picked out and small gold can be dissolved with mercury. Mineral gold is mostly associated with other metals, including silver, platinum, zinc and other metals, which were called alloy gold before other metals were put forward. Ore gold is produced in different mines and contains different other metals, so the fineness varies, generally between 50% and 90%.
Placer gold is produced at the bottom of the river or in low-lying areas, so stones and sand are mixed together and gold is leached. The placer gold mine originated from the mine. Because the gold ore is exposed on the ground, after a long period of wind and rain, the rock is weathered by the north wind and cracked, which makes the gold leave the vein with sediments, naturally deposit in the sand and deposit as a gold-bearing layer at the bottom of the river or under the sand, thus forming placer gold mine. The characteristics of placer gold are: the particle size is different, the big one is like broad bean, the small one is like fine sand, and the shape is different. The color varies with the fineness. More than 90% is red and yellow, eight is light yellow and seven is cyan yellow.
Mature gold is the gold after smelting and purifying raw gold, which is generally high in purity and fine in density, and some of it can be directly used in industrial production. Common are gold bars, nuggets, ingots, various ornaments, utensils, gold coins and industrial gold wires, sheets and plates. Because of different uses, the required fineness is different, or because there is no purification equipment, only unpurified gold is melted, or the purity is not enough to form gold with different fineness. People are used to being divided into pure gold, red gold and colored gold according to their fineness. According to the different gold content, it can be divided into solid gold, mixed color gold and K gold.
Purified gold with high purity is called pure gold, which generally refers to gold with purity above 99.6%.
Red gold and pure gold are close in pride, but the standard of red gold varies with time and place. The gold sold in the international market is called red gold with a purity of 99.6%. Domestic red gold is generally between 99.2% and 99.6%.
Color gold, also known as "secondary gold" and "tidal gold", refers to gold with low fineness. Due to the different contents of other metals, the purity of these gold is as high as 99% and as low as 30%.
According to different kinds of metals, gold can be divided into pure gold, mixed gold and k gold. Clear gold means that gold is only mixed with silver, regardless of its fineness. Clear gold is more common in gold bars, ingots, blocks, various utensils and gold ornaments.
Mixed color gold means that besides silver, gold also contains other metals such as copper, zinc, lead and iron. According to the different types and quantities of metals, it can be divided into small mixed gold, large mixed gold, bronze mixed gold and lead mixed gold.
K gold refers to the gold prepared by silver and copper in a certain proportion according to the formula that pure gold is 24k. Generally speaking, the more silver in K gold, the bluer the color; If the proportion of copper is large, the color is purple. In the early days of liberation, China's K gold was calculated according to the standard of15% per K4. After 1982, it has been harmonized with international standards, taking1666% as the standard.