Tunguska Ilmenite : 2008

Photograph by

Dee Breger

About this image

Scanning electron micrograph of a sample of the mineral ilmenite from the region around Tunguska, Siberia. This piece of the specimen is about 30 micrometres wide. On 30 June 1908 a fragment of a comet or asteroid crashed into the atmosphere, exploding at an altitude of 5-10km with an explosive energy equivalent to 10-15 million tons of TNT. The explosion flattened over 80 million trees over an area of 2150 square kilometres. The shock wave generated altered the structure of many minerals that were found close to the surface. A piece of the comet or asteroid may have survived to hit the Earth and form a crater, now called Lake Cheko, where this specimen was found. The checkerboard pattern here is typical of instantaneous mechanical stress. The original monochrome image was digitally enhanced using a variety of graphics techniques to highlight structural features. Lamont-Doherty Earth Observatory, Columbia University, New York, U.S.A