Question

If a mineral lacks cleavage, it will

a. break along planar surfaces with specific orientations.
b. break along irregular or conchoidal fractures.
c. not break apart unless melted.
d. not break apart unless dissolved.

Answer 1

If a mineral lacks cleavage, it will break along irregular or conchoidal fractures, which are surfaces that do not exhibit the flat, planar orientations characteristic of cleavage.

Step-by-step explanation:

If a mineral lacks cleavage, it will break along irregular or conchoidal fractures. Cleavage in minerals refers to their tendency to break along flat surfaces due to weak chemical bonds in certain directions.

However, when no such planes of weakness exist, the mineral exhibits what is known as fracture, resulting in a less predictable and more irregular breakage pattern. Fractures can be conchoidal (curved and shell-like) or simply irregular, not following any flat or planar surface.

A common example of conchoidal fracture is seen in quartz. It is important to be aware that the presence of what might appear to be flat surfaces does not necessarily indicate cleavage; such surfaces need to be examined closely, often with a hand lens, to determine if they are truly cleavage planes.