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
TYPES OF FOSSILS figure 1.2 TYPE OF FOSSIL:- There are different types of fossils, each of which has been incredibly beneficial in telling us about the life on earth that existed billions of years ago. figure 1.3 ( mold fossil ) MOLD FOSSILS 1. These are fossilized imprints that are made within a substrate. The substrate, in this case, is usually a rock or sediment. The fossil makes use of these substrate components in order to leave their mark on them. They are quite similar to the negative impressions left by an animal or a plant. 2. Mold fossils are primarily formed through a process called ‘leaching.’ In this process, the shell material of rock, for instance, is removed, leaving behind a hollow or gap in the rock. The hard part of the or