Igneous rocks -
1. texture, can be smooth, fine-grained, coarse-grained, glassy, or porphyritic.
2. origin, geologists use this to study to know where it was found, like it could be formed by hardened magma under the earth's surface.
3. mineral composition, some of these rocks had other minerals that help us find all the exact minerals. (like a tree diagram)
Sedimentary Rocks-
1. the only rocks with fossils, trace fossils, or sedimentary features.
2. composed of strata (layer) or laminations (bed)
3. sedimentary rocks have grains instead of crystals.
4. Metamorphism destroys fossil evidence and lava destroys its organic material before the fossilation can take place.
Metamorphic Rocks-
1. rarely have fossils & they are classified by these textures and compositions
2. they can react with acid. may or may not have a curved or bent foliation
3. can be formed w/ only one mineral & they rarely have pores or openings.
