MINERALS AND ROCKS BY-AKANKSHA SONI
The earth is composed of various kinds of elements. They are in solid form above the crust and in liquid in the interior. bout 98% of crust is composed of 8 elements. These elements are rarely found exclusively but combined with other elements to make various substance. lhey are called as minerals Table 5.1 : The Major Elements of the Earth's Crust A The basic source of minerals is MAGMA in interior. SL No By Weightes) Elements hen it cools, crystals of minerals appear 1. Oxygen 2. Silicon 4. Iron 5 6 7. Potassium 8. Magnesium 9 46.60 27.72 8.13 5.00 3.63 2.83 2.59 2.09 1.41 PHYSICAL CHARACTERSTICS- External form, fracture, lusture, color, transparency, structure, hardness etc Calciumm Sodium Others
Metallic minerals- They contain metal content. * Precious- Gold, silver, platinum etc Ferrous: Iron and oher metal often mised with ronto form steel Precious- Gold, silver, platinum etc Ferrous- Iron and other metal often mixed with iron to form steel Non- ferrous- Copper, lead, zinc, tin, aluminium etc. Non-metallic minerals- Do not contain metal content. Eg- Sulphates, nitrates etc ROCKS Crust is composed of rocks.They may be hard or soft and vary in colors On the basis of formation- 1) Igneous rocks Also known as primary rocks because they form when magma cools and solidifies olidification can occur in the earth or may be on crust they are classified based on texture. It shows arrangement of grains. If cooled slowly, grains may they are classified based on texture. It shows arrangement of grains. If cooled slowly, grains may be large and vice versa. Eg- granite, basalt etc
Types of igneous rocks Sedimentary 2) Sedimentary rocks Rocks when gets denuded by denudation agents (broken up).They are transported and gets deposited. This deposition through compaction turns into rocks. Process is known as LITHIFICATIO . N. So we can see a number of layers on these rocks 3)Metamorphicrocks Rocks change their form under action of Pressure, Volume and Temperature (PVT) Metamorphism occurs in consolidated rocks when they undergo recrystallisation
Some rock grains get arranged in layers or lines and called s FOLIATION and Some rock grains get arranged in layers or lines and calleds F LINEATION Some rocks appear in layer of dark and light shade called as BANDING. Eg Quartzite, slate, schist etc
ROCK CYCLE THE ROCK CYCLE Rocks do not remain in original form and keep on changing his cycle is also a continuous process that transforms old rocks into new ones. Sedimentary Rock gneous Igneous are primary rocks. They can be changed into either sedimentary or metamorphic depending on conditions. Rock Sedimentary rocks themselves can turn in fragments and can form sedimentary rocks. y rock can be carried down in the mantle through subduction or convergence and it melt down due to increase in temperature and turn in magma, original source of igneous
With your logic and understanding, find out where can you find these rocks casily?