Rock and Minerals

What is a rock?

An aggregate of two or more minerals.

Define mineral.

A naturally occurring, usually inorganic, homogeneous solid with a definite (but usually not fixed) chemical composition and an ordered atomic arrangement.

Who is considered the father of mineralogy?

Georgius Agricola, for his publication 'De Re Metallica' in 1556.

What is Moh's Scale of Hardness?

A scale that ranks ten common minerals from 1 (softest) to 10 (hardest) to compare hardness.

What is a crystal?

A homogeneous solid possessing long-range, three-dimensional internal order.

What characterizes an euhedral crystal?

A crystalline solid with well-formed faces.

What is cleavage in minerals?

The tendency of minerals to break parallel to atomic planes.

What are polymorphs?

Two minerals with the same chemical composition but different internal ordering and thus different external forms.

Define silicates.

Minerals that contain silica (Si) and oxygen (O) bound together in the form of the silica tetrahedron.

Name the seven crystal systems.

Triclinic, Monoclinic, Orthorhombic, Tetragonal, Hexagonal, Isometric (cubic).

What does 'crystallization' refer to?

The process by which matter becomes crystalline from a gaseous, fluid, or dispersed state.

What is the structure of nesosilicates?

Independent tetrahedra.

What are the characteristics of dark silicates?

Typically ferromagnesian, includes minerals like Olivine, Pyroxene, Amphibole, Biotite, and Garnet.

What is the difference between anhedral and subhedral crystals?

Anhedral crystals lack well-formed faces, while subhedral crystals have imperfectly developed faces.

Who recorded the first written work on minerals?

The Greek philosopher Theophrastus.