Stone is the word that popularly refers to loose pieces of rock. it's a body hard and solid and widely used in construction.
In the human body, on many occasions, the formation of stones occurs in certain organs of the body, such as kidneys, bladder, etc. These stones are popularly known as "stones", and that is why the expression "kidney stone" is quite common.
The branch of geology responsible for the study of rocks is known as petrology.
Precious stones
Precious stones they are rare and beautiful minerals that have a high commercial value. Precious stones are usually transformed through cutting and polishing, for use in the jewelry business and for decorative purposes. Some of the best known gemstones are: diamonds, emeralds, rubies and sapphires.
Formation
To understand how a stone appears, it is necessary to know its formation.
The process starts when magma, originating from the planet's hot interior, is expelled to the earth's surface. When this dense liquid comes into contact with the surface, a thermal shock occurs due to the large temperature difference, causing the lava to cool and thus turning into rocks, however, only those that are of sufficient size are considered rock for such. From that moment on and over time, nature is in charge of the erosion process responsible for fragmenting parts of the rock, giving rise to stones.
The term "stone" is used in several types of minerals, and beyond, which have characteristics similar to common stone, more properly the fragments of solid and hard body, for example: gemstones, salt stones, crystal stones etc.