How can you tell the difference between an igneous rock and a metamorphic rock?

Answer 1

Igneous rocks are called fire rocks and are formed either underground or above ground. Underground, they are formed when the melted rock, called magma, deep within the earth becomes trapped in pockets. As these pockets of magma cool slowly underground, the magma becomes igneous rock . Igneous rocks are also formed when volcanoes erupt, causing the magma to rise above the earth's surface. When magma appears above the earth, it is called lava. Igneous rocks are formed as the lava cools above ground.

Metamorphic rocks are rocks that have "morphed" into another kind of rock. These rocks were once igneous or sedimentary rocks. How do sedimentary and igneous rocks change? The rocks are exposed to great heat and pressure from depth of burial or exposure to tectonic forces, and this causes them to change. The change is reflected in the recrystallization of certain mineral crystals, or even the disappearance of some minerals and the appearance of new minerals. Metamorphic rock often displays foliation, in which the minerals are aligned in bands or thin layers perpendicular to the force that was applied in their metamorphosis. Igneous rocks do not display layering.

Answer 2

All three rocked differ most importantly in how they were formed. Igneous rock is formed in volcanic environments. Heated magma exits volcanoes, cools off rapidly or slowly (which also effects the type of rock produced) and forms igneous rock. Its appearance will be without organic particles or any stratification, and its grain is typically fine. Sedimentary rock is formed in layers referred to as stratification, as moving water carries particles ranging in size as well as organic material and deposits them on the ground floor depending on the speed of the water that is travelling. Its grains can range from fine to coarse and its colors are usually reddish due to iron content. Metamorphic rock is formed from the previous two types undergoing a process of compression. The molecular structures change under the heat and pressure of metamorphosis, thereby changing the color and properties of the rock. This process can be exemplified by the existence of coal, which is organic sediment that has been subjected to a metamorphic environment. It will typically be much more dense and usually has distorted layers and darker colors due to lack of oxygen.