Final answer:
Cleavage refers to the characteristic way minerals break along certain planes, revealing information about their structure and history, while luster describes how light interacts with a mineral's surface.
Step-by-step explanation:
The property of cleavage refers to the way minerals break along specific planes of weakness within their crystal structure. These planes, called cleavage planes, are where the chemical bonds are weakest. Cleavage is a vital characteristic for mineral identification because it provides insight into the mineral’s structure and formation. For instance, amphibole and pyroxene can be differentiated by their cleavage properties, despite having similar physical characteristics. Recognizing cleavage involves examining the reflective nature of a mineral surface, which can be enhanced by shining light upon it, making the cleavage planes visibly distinct.
In comparison, luster deals with how light interacts with a mineral's surface. It is categorized mainly into metallic and non-metallic lusters, where metallic luster means light doesn’t pass through the mineral's atomic structure, while non-metallic minerals allow some light penetration. Nevertheless, a shiny appearance does not always mean the mineral has a metallic luster.
Understanding the concept of cleavage is essential for geological studies, as it can reveal much about a rock’s geologic history and mineral content. Furthermore, using modern tools like a cell phone flashlight or a hand lens makes identifying cleavage in minerals a more accessible task for students and professionals alike.