Last year I introduced Jamey to Tammy and Eddy Thomason at Thomason Stone and Supply. Here's a picture of the PSA at their booth this year. Tammy wrote a great article about magnesite selling as variously named turquoise in the G&LW Show book.

Many vendors still sell all the colors of magnesite as a type of turquoise. Magnesium Carbonate, MgCO3, a mineral that is not related to turquoise in any way. Turquoise is a hydrated phosphate of copper, aluminum and often iron. Turquoise is a variable mineral with a variety of chemical formulae representing it. One is Cu(Al,Fe3+)6[(OH)4(PO4)2 + 4H2O (sorry this forum does not do equations well) Turquoise is a copper mineral. ALL forms of turquoise contain copper. Magnesite contains NO copper.

--Russ (Rings & Things)