Surface dissolution features and contact twinning in natural diamonds

摘要

Contact twinning with the so-called "macle" form or other shapes are often found in natural diamond crystals. However, the surface microtopographic features associated with twinning have been less investigated. Here, the surface dissolution and growth features seen on the twin boundaries, including the re-entrant angles revealed by differential interference contrast microscope and SEM techniques in 170 natural diamond crystals mainly from Argle mine, Australia are described and summarized. The hexagonal pits, rhombic pits along with higher symmetry observed at the twin boundaries together with dislocations and their formation processes are discussed.