CHERT Chert is a sedimentary rock of biochemical origin. It is likely the result of the accumulation (in the deep ocean, far from land) of the silica shells of various micro-organisms such as diatoms. Note that the similar rock chalk is composed of the calcite shells of different micro-organisms. |
See Steve's video interview about asteroid capture at Moonandback: Part 1 Part 2 Part 3 |
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See Steve's blog Ramblings On The Future Of Humanity (recent post) A Project Plan for Space Based Solar Power
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