Final answer:
The described mineral with perfect cleavage and variations like selenite, alabaster, and satin spar is gypsum, a common mineral in igneous rocks. Its distinctive cleavage and physical properties like density and sound it makes when struck are key identifiers.
Step-by-step explanation:
The mineral described with perfect cleavage in 1 direction, poor cleavage in 2 others, and that is white in color with variations such as selenite, alabaster, and satin spar is likely gypsum. The description matches the characteristics of this mineral commonly found in igneous rocks.
The properties of gypsum include being nonmetallic, dense, and having the ability to produce a clinking sound when struck. Additionally, gypsum can have elongated crystals or be prismatic and might show striations on some cleavage surfaces.
The mineral's cleavage patterns help geologists and students alike understand its composition and the conditions under which it formed.
When working with minerals, notably gypsum, the characteristics of their cleavage and fracture are crucial for identification. Cleavage refers to the way a mineral will break along certain planes where chemical bonds are relatively weaker, producing smooth, flat surfaces.
For gypsum, the cleavage is perfect in one direction and poor in two others, which suggests certain structural properties about the mineral at a microscopic level.