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水菱镁矿(hydromagnesite)虽在很早以前就被发现,但在我国却一直未有这方面的正式报导。同时目前所知在捷克斯洛伐克、意大利、美国、法国及苏联,该矿物均产在镁质超基性岩(蚀变产物蛇纹岩)及菱镁岩中,为低溫热液及次生产物。与水镁石、纤维菱镁矿及蛇纹石等相伴。我们所见水菱镁矿产在由白云菱镁大理岩蚀变而形成的硼镁石蛇纹岩中。其富集地段离地表仅数米,为表生作用造成。该处错动发育,硼镁石蛇纹岩被错成角砾状,并有孔洞产生。沿孔洞先后有金云母及绿泥石充填,水菱镁矿就发生在未被充填之残余孔洞中。水菱镁矿之形成环境为自由空间,它大多垂直或斜交洞壁而生长,其外有时还覆盖一层方解石薄膜,最外为残余孔洞(照片1、2)。在同一蚀变体之错动不发育地段很难见到它的出现。水菱镁矿虽不是一种少有矿物,但分布局限性很大,且不呈大规模堆积。因此,对其矿物性质及形成条件进行探讨,具有一定意义。
Although hydromagnesite was discovered long ago, it has not been formally reported in our country. At the same time, it is known that in Czechoslovakia, Italy, the United States, France and the Soviet Union, the minerals are all produced in magnesian ultrabasic rocks (alteration product serpentinite) and magnesite, which are low-temperature hydrothermal fluids and secondary products. And brucite, fiber magnesite and serpentine accompanied. The hydromagnesite mineral we have seen is in the borophite serpentinite formed by the alteration of the Baiyin Magnesite Dali. Its enrichment lot only a few meters from the surface, as a superficial effect. The area is misdirected, and the borophite serpentinite is wrongly brecciated and has holes. There are phlogopite and chlorite filling along the hole, and water magnesite occurs in the remaining hole that is not filled. Hydrochlore is formed in a free-space environment that grows mostly vertically or diagonally, and sometimes contains a layer of calcite film, most often the remaining holes (Photos 1, 2). It is very difficult to see the emergence of the same alteration body in the undeveloped area. Although the water magnesite is not a rare mineral, but the distribution of great limitations, and did not show large-scale accumulation. Therefore, its mineral properties and formation conditions to explore, has a certain significance.