Question

cleavage and fracture are properties that describe how minerals break. cleavage describes how a mineral breaks into even, flat surfaces. a minerals cleavage is measured by quality and number of sides. a mineral has perfect cleavage if it leaves no rough surface at all when broken. cleavage is poor if there is more of a rough surface created. some minerals only have cleavage along one side. others have cleavage on two or more sides. feldspar has two cleavage planes that intersect at right angles.
fracture describes how a mineral breaks into surfaces that arent flat or even. some minerals can have a splintery fracture, like pectolite. others have an earthy fracture. they break into crumb - like pieces, like soil. other minerals have fracture that is rounded like a shell. sulfur has this fracture, which is called conchoidal.
the cleavage of a mineral
choose one option
a must happen on two or more sides of a mineral.
b is perfect if it creates a smooth, flat surface.
c cannot create 90 degree, right angles.
d can occur in rounded, conchoidal shapes.

Explanation:

• Option A: The text says "Some minerals only have cleavage along one side", so it's not a must to have on two or more sides.
• Option B: The text states "A mineral has perfect cleavage if it leaves no rough surface at all when broken", which implies a smooth, flat surface (as rough surface is the opposite of smooth and flat).
• Option C: The text mentions "Feldspar has two cleavage planes that intersect at right angles (90 degrees)", so this option is wrong.
• Option D: Conchoidal fracture is a property of fracture (not cleavage) as per the text "Sulfur has this fracture, which is called conchoidal".

Answer:

B. is perfect if it creates a smooth, flat surface.