Quartz Quartz is hexagonal and commonly occurs as crystals ranging in size form microscopic to crystals weighing several tons. Where it crystallizes unhindered by other crystals, such as in cavities in rock or in a liquid containing few other crystals, it shows well-developed hexagonal prisms and sometimes showing apparent hexagonal pyramids or dipyramid. When it crystallizes in an environment where growth is inhibited by the surroundings, it rarely show crystal faces. It is also found as microcrystalline masses, such as in the rock chert, and as fibrous masses, such as in chalcedony. Vitreous lusture. As visible crystals, Quartz is one of the more common rock forming minerals. It occurs in siliceous igneous rocks such as volcanic rhyolite and plutonic granitic rocks. It is common in metamorphic rocks at all grades of metamorphism, and is the chief constituent of sand. Because it is highly resistant to chemical weathering, it is found in a wide variety of sedimentary r
THE HIMALAYAN UPLIFT DURING TRIASSIC PERIOD –GONDWANA LAND START TO BREAK INTO INDIA ,SOUTH AFRICA , AUSTRALIA, ANTARTICA, IRAN ,ETC….. DURING 55 Million Age THE INDIAN PLATE COLLIDED WITH EURASIAN PLATE First, reconstruction of the speed of the Indian plate in the geologic past indicates that the plate motion drastically decreased in the Eocene. During Cretaceous and Paleocene times (85-55 Ma), India moved northward at rates of 15-20 cm per year but slowed down to only about 5 cm per year by 45 Ma (These data come from examination of magnetic anomalies of rocks on the Indian Ocean floor and from paleo-magnetic analyses of rock samples from the Trans-Himalaya by various scientists) PHASE 1 : THE TRANS HIMALAYAN UPLIFTMENT First mountain range is trans - Himalayan igneous arc, Indus and t-sangpo are the first rivers to transport sediment in Eocene period . Trans-Himalaya indicate that these rocks rapidly cooled and eroded at ab