The Dalnegorsk boron deposit obviously has no genetic analogues among the known world boron deposits and that inspired many researchers to investigate its peculiarities. Despite the great amount of works devoted to this deposit, problems on its genesis and the source of boron remain unclear. Our aim is to solve them. The Dalnegorsk borosilicate deposit is developed industrially for boron and for specimens of danburite, datolite, and axinite by gemmologists and collectors. This deposit is a bed-like body of skarns extending for 3.5 km in accordance with folding. Limestone blocks are skarned, and terrigenous rocks are less skarned; the thickness of the skarned rock body reaches 540 m and it extends to a depth of 1.7 km.
Physical and chemical conditions of formation of boron minerals in the Dalnegorsk borosilicate deposit have been determined. The temperature of datolite formation is 150oC – 185oC, KCl prevails in the saline system composition, but NaCl and MgCl2 are also present. The temperature of danburite formation is 270oC – 280oC, NaCl, KCl and CaCl2 are present in the phase composition of the saline system. The temperature of axinate formation is 360oC – 380oC, the saline system contains KCl, MgCl2 and B. The solution concentration for determined temperature of axinate homogenization is 10.1% and is equivalent to CaCl2.
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