Minerals and Rocks
The Earth's lithosphere is composed of a small amount of soil with all the rest being rock. Rocks are mainly made up of minerals that form its basic building blocks.
There are many types of naturally-occurring but most rocks are relatively simple. Five to six types of minerals make up most of the rocks on Earth and these minerals are known as "Rock-forming Minerals".
Common rock-forming minerals include Feldspar, Quartz, Mica, Amphibole, Pyroxene, Olivine, Calcite and Clay. Feldspar is the most common and accounts for 58% of the total crust. Quartz, Mica, Amphibole, Pyroxene and Olivine all account for over 1% of the Earth's curst as well. Clay minerals are formed through the weathering of Feldspar and Kaolinite is the most common. Calcite on the other hand is the main component in limestone. 

Minerals and Fossils
Fossils are the traces left by the remains or activities of ancient creatures. Dinosaur bones or footprints left in the rock strata are all fossils, though the bones are referred to as body fossils while the footprints they leave are referred to as "cast fossils".
When a creature dies, its body usually decomposes, breaks down and eventually disappears. In very rare circumstances, the remains or traces are buried deep under sediment. They are then preserved until everything is replaced by minerals and over time, fossils are created. When the organic matter is replaced by minerals the resulting fossil usually becomes very hard and heavy. The color changes after substitution as well. For example, the silicified wood within the Petrified Forest National Park in Arizona, USA, has been replaced by agate to form kaleidoscope-like colors. The original tissue has long since disappeared but the outline of the growth rings and tree barks remains plain to see.

National Museum of Natural Science