The Collaborative International Dictionary of English v.0.48:

Ralstonite \Ral"ston*ite\ (r[add]l"st[u^]n*[imac]t), n. [So
   named after J. G. Ralston of Norristown, Penn.] (Min.)
   A fluoride of alumina and soda occurring with the Greenland
   cryolite in octahedral crystals.
   [1913 Webster]