Amongst other things I have painted aliens and based them on dirt from Roswell and Yorick’s skull on dirt from Kronborg Castle, the inspiration for Elsinore. My Hebrew army is based with soil from Megiddo, and I have dirt from The Alamo waiting for me to paint Davy Crockett and stones from the Place de la Concorde in case I get a guillotine one day.
Splendid! I have not previously (outside the MEXE soil survey) encountered a soil nerd, but that, I reckon, is True Grit.
I am reminded of a cartoon from “Military Modelling”, or possibly “Battle for Wargamers”, back in the old-timey times, that showed one bloke scrutinising another’s model of a hoplite with a tremendously close scrute, and saying “The dust under the toenails is the wrong colour for Thermopylae”.
I trust and believe that if that were to happen to you, you would catch the pontificating pedantic prodnose a smart thwack athwart the sinciput and declaim in stentorian tones “It’s *from* Thermopylae, you buffoon!”
All the best,