Złoto z kamieniołomu Złoty Jar k. Złotego Stoku (Sudety)
Abstract
GOLD MINERALIZATION IN THE ZLOTY JAR QUARRY NEAR THE ZŁOTY STOK AS-AU DEPOSIT (SUDETES, SW POLAND)
Summary
In the results of detailed microscopic study primary gold bearing mineralization was found in the diopside-tremolite-calcite-tale rocks from the Złoty Jar quarry localized near As-Au Złoty Stok deposit (Sudetes). Gold mineralization was due to metasomatic processes developed in the contact zone between highly tectonized sedimentary volcanic rock complex of upper Proterozoic-Iower Paleozoic age and the Variscan Kłodzko-Złoty Stok granitoid massif. Most gold occurs as invisible and as submicroscopic and microscopic-size particles in ore minerals, quartz veinlets and fissures among rock minerals. Invisible gold was determined using microprobe analyses in arsenopyrite (up to 1.4 wt. %), bismuthynite (up to 2.3 wt. %), loellingite (up to 0.8 wt. %) and Ni, Fe, Co sulphoarsenides (0.4 wt. %). Three types of native gold depend on chemical content and microscopic studies were recognized: rich in silver (Electrum 31.6 wt. % Ag), rich in bismuth (35 wt. % Bi) and poor of admixtures (15 wt. %). Visible gold was observed mostly as inclusions from 5 to 20 Ilm in size among (Fe, Co, Ni) sulphoarsenides and sulfides in carbonated and silicicated cale-silicates rocks (gold contents in these rocks are up to 10 g/t). Gold-bismuth myrmekites in sulphoarsenides were also observed. Preliminary results of fluid inclusion studies in metasomatic minerals (scheelite, garnet, pyroxene) show temperatures of skarn-Iike crystallization at 464-480° C and from 250°C up to for crystallization of quartz veins containing ores with native gold (Mikulski, 1996). Processes of redistribution of primary gold from loellingite-arsenopyrite mineralization were wide developed and carried out by sulfur-bearing solutions at 250-350°C and near neutral to alkaline environments with dominant role of hydrosulphide complex Au(HS)2-.
Summary
In the results of detailed microscopic study primary gold bearing mineralization was found in the diopside-tremolite-calcite-tale rocks from the Złoty Jar quarry localized near As-Au Złoty Stok deposit (Sudetes). Gold mineralization was due to metasomatic processes developed in the contact zone between highly tectonized sedimentary volcanic rock complex of upper Proterozoic-Iower Paleozoic age and the Variscan Kłodzko-Złoty Stok granitoid massif. Most gold occurs as invisible and as submicroscopic and microscopic-size particles in ore minerals, quartz veinlets and fissures among rock minerals. Invisible gold was determined using microprobe analyses in arsenopyrite (up to 1.4 wt. %), bismuthynite (up to 2.3 wt. %), loellingite (up to 0.8 wt. %) and Ni, Fe, Co sulphoarsenides (0.4 wt. %). Three types of native gold depend on chemical content and microscopic studies were recognized: rich in silver (Electrum 31.6 wt. % Ag), rich in bismuth (35 wt. % Bi) and poor of admixtures (15 wt. %). Visible gold was observed mostly as inclusions from 5 to 20 Ilm in size among (Fe, Co, Ni) sulphoarsenides and sulfides in carbonated and silicicated cale-silicates rocks (gold contents in these rocks are up to 10 g/t). Gold-bismuth myrmekites in sulphoarsenides were also observed. Preliminary results of fluid inclusion studies in metasomatic minerals (scheelite, garnet, pyroxene) show temperatures of skarn-Iike crystallization at 464-480° C and from 250°C up to for crystallization of quartz veins containing ores with native gold (Mikulski, 1996). Processes of redistribution of primary gold from loellingite-arsenopyrite mineralization were wide developed and carried out by sulfur-bearing solutions at 250-350°C and near neutral to alkaline environments with dominant role of hydrosulphide complex Au(HS)2-.