What are some nine-letter types of rock?

16 of the 78 types of rock in Icillion have exactly 9 letters, for example Limestone, Sandstone and Quartzite.

Which nine-letter types of rock start with S?

S is the most common first letter here, with 3 names, such as Sandstone, Siltstone and Soapstone.

Science · lists

Stuck on a crossword or a word game? 16 types of rock have exactly 9 letters, from “Claystone” to “Soapstone”.

16 of the 78 types of rock have exactly 9 letters (21%).
Most start with S (3), G (2) and P (2).
Only names of one word are counted, and only their letters: spaces, hyphens and apostrophes are not.

What are some nine-letter types of rock?: 16 of the 78 types of rock in Icillion have exactly 9 letters, for example Limestone, Sandstone and Quartzite.
Which nine-letter types of rock start with S?: S is the most common first letter here, with 3 names, such as Sandstone, Siltstone and Soapstone.

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