Crystal Habit of Magnesium Oxide Smokes

Crystal habit of magnesium oxide smokes was observed by using a magnetic electron microscope. Interference fringes appearing in crystals and the contour forms of crystals in images were observed in order to determine the twin plane and the orientation of the crystals. As the results it was found that there existed many crystals having (111) twin beside normal cubic one. Extraordinary crystals having particular cut section were observed and it was known that their cut sections may be perhaps (111) planes. It was also found that there were many interesting modes of connection of cubic magnesium oxide crystals.