Final answer:
The term used to describe the formation of smooth surfaces where a mineral tends to break is cleavage. This characteristic is identified by the presence of flat, reflective planes on the mineral, distinguishable through careful observation with a light source.
Step-by-step explanation:
The term used to describe the tendency of a mineral to break along planes of weakness and form smooth surfaces is cleavage. Cleavage occurs when minerals break along planes where chemical bonds are the weakest, creating flat surfaces called cleavage planes.
Several factors like the number of planes, the angles between them, and the presence of light reflecting surfaces are used to identify cleavage. An easy way to identify cleavage is by using a cell phone flashlight or sunlight to look for a brilliant reflection on the mineral's surface, which indicates a cleavage plane.
It's important to differentiate cleavage from fracture, which defines an irregular break in the mineral often along planes without weak chemical bonds and results in uneven surfaces.
To correctly identify minerals, observing the details with a hand lens for signs of cleavage and recognizing the mineral's physical features, such as hardness using the Mohs' scale of mineral hardness and examining the luster, whether it's metallic or non-metallic, are essential steps.