Bathvillite

Bathvillite is a naturally occurring organic substance. It is an amorphous, opaque, and very friable material of fawn-brown color, filling cavities in the torbanite or Boghead coal of Bathville, Lothian, Scotland. It has a specific gravity of 1.01, and is insoluble in benzene.[1] It may resemble wood in its final stage of decay.[2]

References

1.  One or more of the preceding sentences incorporates text from a publication now in the public domain: Chisholm, Hugh, ed. (1911). "Bathvillite". Encyclopædia Britannica. Vol. 3 (11th ed.). Cambridge University Press. p. 521.
2. Dana, James Dwight; Brush, George Jarvis (1884). A System of Mineralogy: Descriptive Mineralogy, Comprising the Most Recent Discoveries. J. Wiley & sons. p. 742. Bathvillite.