Last seen in:
- Newsday.com - May 13 2021
- L.A. Times Daily - Jul 22 2018
- The Washington Post - Jul 22 2018
- Newsday.com - Feb 16 2018
- Newsday.com - May 22 2016
- Newsday.com - Jan 26 2014
- Newsday.com - Oct 15 2009
- USA Today - Mar 25 2009
- The Telegraph - QUICK CROSSWORD NO: 25,189 - Jan 1 2007
- L.A. Times Daily - Aug 27 2006
Related Clues:
- Easily cleaved rock
- Oil source has excited the French
- Product of clay compaction
- Introduction of secure, healthy, source of gas
- Oil source has damaged the French
- Some mudrock
- Frackable rock
- Rock formed from clay
- Earth's crust, mostly
- Rock in which fossils can be found
- Rock source of petroleum
- Mineral bore, for instance?
- Thin-layered sedimentary rock
- Hospital in transaction for source of gas
- Rock involved in fracking