Pure silica (SiO, ) exists at room temperature in the four different modifications: quartz, tridymite, cristobalite, and fused silica. The first three are crystalline, but fused silica is a non-crystalline solid, a glass. Tridymite, cristobalite, and fused silica are metastable, but at room temperature they do not invert within measurable time to the only thermodynamically stable modification, ...

Archean Quartzose Rocks at Akilia, Greenland Fedo and Whitehouse (1) presented data to support their hypothesis that granulite grade quartz magnetite rocks on the island of Akilia, southwest Greenland—which are conformably interposed with pyroxenite and hornblendite units that date from before 3830 million years ago (Ma) (2–4)—had a metasomatic ultramafic igneous origin. They offered that inter...

Based on cosmogenic 10Be and 26Al analyses in 15 individual detrital quartz pebbles (16–21 mm) and cosmogenic 10Be in amalgamated medium sand (0.25–0.50 mm), all collected from the outlet of the upper Gaub River catchment in Namibia, quartz pebbles yield a substantially lower average denudation rate than those yielded by the amalgamated sand sample. 10Be and 26Al concentrations in the 15 indivi...

Greisenization is typically linked with highly fractionated granites and often associated hydrothermal vein systems. Late to postmagmatic metasomatic processes involve the enrichment of volatile components such as boron halogens well several metallic elements. The purpose this study reveal main effects paragenetic sequences related mineralizations in Highiş granitoids, Romania. In a natural out...

roudgaz prospect area is a cu, sn, pb, zn, and au polymetal vein system located to the southeast of gonabad and in the northeast of lut block. oxidan subvolcanic tertiary rocks with monzonite to monzodiorite porphyry composition intruded the metamorphic rocks of middle jurassic. the majority of intrusive bodies are affected by carbonation, argillic, sericitic, and silicification-tourmaline alte...

Abstract Black shales may serve as an important source of metals such Co, Ni, or As, largely due to anoxic euxinic conditions in association with high concentrations sulfur leading efficient scavenging and transport from seawater into the seafloor sediment. We report on unusual type Au mineralization newly discovered Ediacaran trench-slope black Bohemian Massif, Czech Republic. The enrichment i...


 The article describes Reza gold deposit of Ugur exploration area located in Geda- bek Ore District the Lesser Caucasus NW Azerbaijan. It is established that main mineralization consists hematite-barite-quartz-kaoline veins- veinlets and breccia, pyrite stock-stockverk quartz-sulfide veins. On orebody surface center secondary quartzites with vein-veinlets barite-hematite have occured over...

Hydrothermal quartz samples collected from the Fujiashan and Yipanqiu deposits in southeastern Hubei Province, China have been investigated by analytical combination of optical microscopy, scanning electron inductively coupled plasma emission spectroscopy, conjunction with conventional beneficiation processing to evaluate their potential as sources high purity (HPQ) a commercial perspective. Mi...