Parallel grooves, also known as striae or striae, are a series of shallow grooves that run parallel to each other. They are often found in rocks, minerals, and other materials, and can be used to identify them. The term 'striae' is derived from the Latin word for 'FURROW' or 'GROOVE'. The grooves are usually very thin and can be seen with the naked eye. They are often used to study the structure and composition of materials.