Cleavage is a property of minerals where they break along planes of weaker atomic bonds, creating flat surfaces, which is distinct from irregular fracture surfaces and reveals geological information.
The tendency of minerals to break along planes of weaker atomic bonds, producing flat shiny surfaces, is known as cleavage. This phenomenon occurs when sufficient force is applied, causing a layer of ions to slip over another layer along a cleavage plane, which quickly weakens their attraction and leads to physical cleavage. Since ionic solids lack mobility of 'ions,' these solids tend to be electrical insulators. It's essential to use a hand lens to examine the surfaces closely as minerals can break in predictable (cleavage) or irregular (fracture) ways.
Understanding cleavage is crucial for identifying minerals, as it can reveal information about a rock's geologic history. For example, the difference in cleavage between amphibole and pyroxene minerals can indicate the conditions under which they formed. Surface defects, such as plane defects and line defects, also play a role in the mechanical properties of minerals and can influence their behavior during physical stress.
In summary, cleavage is a property that reveals the structural weakness of minerals along which they can break into flat surfaces when stressed, while also providing insight into the material's composition and formation history.