The genetic relationship of crystal pockets and quartz veins, and the origin of cavities
Abstract
In the early stages of studying the piezo-optical quartz deposits of the Northern Urals, some geologists believed that crystal pockets had no genetic connection with quartz veins. Geologists came to this conclusion because at that time the bulk of piezo-optical quartz was mined not from crystal pockets, but from placers, and geologists did not have enough data to correctly resolve this issue. Later, in connection with the transition to exploration of primary deposits, it was established that in most cases quartz veins and crystal pockets are located in the same fractures. The asymmetrical arrangement of crystal pockets in relation to quartz veins does not give grounds to deny the genetic relationship of the two, but only indicates a later formation of crystal pockets compared to quartz veins. In all likelihood, after the formation of quartz veins, there was a fairly long intermineralization break, after which fracturing and the inflow of hydrothermal solutions resumed. The duration of the intermineralization break can be judged by the sharp change in the nature of the hydrothermal solutions – from highly supersaturated with silica (during the formation of quartz veins) to normal (during the formation of quartz crystals). Consequently, quartz veins and crystal pockets are derivatives of a single magmatic source, but were formed in different phases of a single hydrothermal process.
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