Ganapathy R, Brownlee D E, Hodge P W
Science. 1978 Sep 22;201(4361):1119-21. doi: 10.1126/science.201.4361.1119.
Silicate spherules produced by atmospheric melting of meteoric bodies are probably the most common form of extraterrestrial material on the earth. It has never been possible to positively identify such particles although it has been known for more than a century that silicate spherules of suspected extraterrestrial origin are present in deep-sea sediments. One such spherule has been identified as definitely extraterrestrial since its abundances of nonvolatile trace elements closely match those of primitive solar system material.
