1. some characteristics of common rock specimens are different from each other. a distinction between the shape and structure of the extrusive rocks in depth and shallowness.
2. the human eye is also the naked eye to classify and identify, the key classification is to grasp its structure, structure and composition characteristics. observing the structure of common rock specimens can show a type of rock from its surface, such as those with stomata, almond and rhyolite structure, which are usually erupted in igneous rocks. the stratified structure and surface structure are sedimentary rocks. careful observation of rock structure will enable us to see rocks. classification.
3. when identifying common rock specimens with the naked eye, some minerals are difficult to identify. generally, they can only be judged preliminarily according to the color depth, hardness, specific gravity and the chemical reaction of hydrochloric acid. from its surface gloss, transparency, stripe cracks, and some surface phenomena that can be observed, we can make the next judgment.