Answer:
C. a fixed crystalline structure.
Explanation:
Minerals are natural and materially individual components of the rigid crust. Definition of a mineral:
- They are naturally formed.
- Inorganic
- In general solids.
- They have a defined chemical composition.
- Materially homogeneous.
- Crystals (with ordered atomic structure) or
- Amorphous (without crystalline structure, for example natural glasses).
- Most minerals are crystals.
The minerals may have been formed by inorganic processes or with the collaboration of organisms such as elemental sulfur, pyrite and other sulfides may be formed by reduction with the collaboration of bacteria. Sometimes minerals are part of organisms such as calcite, aragonite and opal, skeletons or shells of microorganisms and invertebrates and apatite can be formed, which is an essential component of bones and teeth of vertebrates.
