| Abstract |
A group of minerals called zeolites, are formed in hydrothermal processes mainly. They are typomorphic minerals of the modern and paleo-hydrothermal ore-forming systems. The are widespread in hydrothermally altered host rock aureoles of modern geothermal fields, in ores and in metasomatites of Cenozoic epithermal gold-silver deposits in the Pacific region (Kamchatka, Kuril islands, Japan, Indonesia, New Zealand, North and South America). Zeolites are minerals-indicators of physicochemical conditions of hydrothermal minerogenesis. Each of specific kind of zeolites can be deposited only in certain temperature, pressure and pH value. Generally, crystallization of hydrothermal zeolites occur in saturated alkaline solutions in wide temperature range and under low pressure. Zeolite group of minerals has high absorbing ability, which may promote concentration of gold. Knowledge of zeolite typomorphic features could be used for more detailed and correct classification of geothermal and epithermal gold-containing objects. This is particularly important for estimation of potential of these objects, revealing of their vicissitude, facial zonality, erosional shearing depth; for detection of “blind”(“hidden”) ore bodies and geothermal reservoirs. At the same time, zeolites, having high absorbing ability, may complicate the processing of gold-containing ores. Zeolites interfere in the technological process of gold extraction, which require special reagents and neutralize their effect. For altered host rocks of the Mutnovsky geothermal high-temperature system, which is one of the biggest in Kamchatka, following groups of zeolites are generic: mordenite, heulandite, lomontite and wairakite. Big amount of scolecite, barerrite, mordenite and lomontite was found in the altered host rocks, metasomatites, and ores of epithermal gold deposits in Kamchatka (Asachinsky, Mutnovsky, Rodnikovy, Baranievsky, Agisky). The presence of mordenite and lomontite in gold-containing ores confirms the genetic similarity of epithermal (paleo-hydrothermal ore-forming) systems with modern. The presence of scolecite and barerrite indicates the more complicated conditions of near-surface volcanogenic gold and silver-bearing ore genesis. |