Lecture 12

Namaskar, in the last lecture we saw about plate tectonics, and in the end we also talked about GPS and the deformation of the Indian plate. Today we will start a new topic which is very important, and in this lecture we will talk mainly about how minerals are formed, and how minerals are formed into rocks, and this topic is very important for us, because when we talk about civil engineering in particular, we talk about rocks and their strength, how much strength is there in it, so these minerals have different strengths, and the rocks that are formed from these minerals, it depends on how strong they are. So we will go into this in detail that how rocks are formed from minerals, and how minerals are formed from these minerals, so what was the sequence of that, so a connection of all these is straight from magma, which is ours, and from that only all the rocks are formed, and if you go back to our earlier lectures, when we talked about rock cycle, in that we talked about the three types of rocks, like igneous, metamorphic, and sedimentary rocks, how they are formed, and what is the cycle of it, but now we will mostly see how minerals are formed, and at what temperatures, at what locations we get them, like I said this is the most important part of it. So the question remains that what is a mineral actually, and the study done on this is called mineralogy, and how minerals are formed, how minerals are formed, what is mineral, how it is studied, this is mineralogy, and how it is formed, so we will see about this in this. So, I said that after plate tectonics, in that in many places it was shown that where magma comes out, and those spreading centers are the main source of it, one of the sources we can say, like we said the second thing, the convergence plate boundaries are there, here there is subduction of the plate, from there also magma is produced, which comes out through the plate boundaries. So, these locations on the earth of plate boundaries also play an important role in forming minerals and rocks. So, if we see the major locations, which are there, where magma comes out from volcanoes, and whatever the spreading centers are, these are yours, so one is your source, which is the convergence plate boundaries, and the other is the spreading centers, which we call the mid-oceanic ridges, and the example of this we told you yesterday, in the last lecture, the mid-Atlantic ridge is the longest, which covers the entire earth. So, these are two very important sources from where minerals come into our hands. So, if we look at it a little more, then we have told the same thing in this picture, that the subduction that is taking place from here, after melting, this magma comes up to you, and because of the lava flow, different types of minerals are formed. So, some portions, some materials, which we call magma, it remains inside, inside the earth, and some come to the surface, so that also plays a very important role, because the temperature, which is there, plays a very important role in this. So, if we take the definition of this, what it means, then you will get different definitions of its minerals at different places. So, somewhere it has been said that a mineral is a naturally occurring homogeneous solid, with a definite composition, and an order of atomic arrangement. So, these three things are told in this, that it is a homogeneous solid, it is inorganically formed, it has a definite chemical composition, and ordered atomic arrangement. So, these three things are told in this, that a mineral is a naturally occurring homogeneous solid, with a definite chemical composition, and ordered atomic arrangements. So, this definition was given in 1968. If we see the second definition, then it is said that a mineral is a body produced by processes of inorganic nature. So, these two things are common here, having usually a definite chemical composition. of magma, free surrounding that facilitates the crystal growth in different direction.