Scanning Electron Microscope (GC-10)
Geologists have a powerful new tool for delving into the world of fine-grained geologic materials. The scanning electron microscope (SEM) allows visualization of tiny features a few ten-millionths of an inch in size. Details much finer than the smaller features visible by using the best light microscopes can be seen. Magnifications of more than 100,000 times, compared with 2,000times with light, can be obtained and with 500 times greater depth of field.

In the SEM a very thin beam of electrons is focused on a small sample and then is scanned across the specimens by electromagnetic lenses. When it hits the sample, it causes secondary electrons to fly off. These electrons are detected and amplified by sophisticated electronic equipment to form pictures on a tube lie a TV screen that can be photographed to provide a lasting record.

Information gained by using the scanning electron microscope has proved useful in exploring for petroleum, metallic ores, clay, limestone and coal.

Pyrite in coal 800 X; Oil formation porosity 2000 X

Our Hoosier State Beneath Us: Geochemistry/Geophysics