* Tektites are glassy stones, generally about the size of a walnut. But some are microscopic in size.
* They come in various shapes — some are button-shaped, some round, some rod-like and others are shaped like tear drops or dumb-bells. They usually have grooved or pitted surfaces.
* They vary in colour. They can be jet black, greenish or amber.
* There's some mystery regarding their origin. Some scientists say they might have been formed when great meteorites slammed into rocks containing sandstone. The impact was so great that the rocks melted and the molten matter was flung high into the atmosphere where it solidified and fell back to the earth as tektites.
Other scientists are of the opinion that tektites are the remains of lava blown out by volcanoes on the moon millions of years ago. The lava solidified into pieces of tiny glass on the way to Earth.