Continuing through the "M" box, another group of collectibles without anything more in the way of information than the hallmark: MSC; M2; MEE; MCR, Div. Of Greb; Mehlos Refinery; and MMM. I have seen photos of MMM ingots in smaller size, +/- 2 oz, with Colorado included in the hallmark, "MMM Colorado", but the example below has nothing more than MMM.
A trio of Mastiff Metals ingots in the three presentation variations I have seen on the obverse to date: hallmark alone, hallmark with weight, and hallmark with name. I have read that the Bull Mastiff hallmark encircled by the words "Faithful Guardian" represents the second variety produced by Mastiff Metals, reportedly the first variety contained the written name only. The third example may be a transitional piece between the two varieties. I believe these date to the early 70's.
Metalrex from Reno, NV, one a shallow pour rectangle and the other in the shape of the State of Nevada.
And finally Mid South Silver and Mid South Smelter. I found a Mid South Silver & Recovery Co. and a Mid South Refinery & Smelters, both formerly in business in Brandon, MS. Nothing to add on the first but Mid South Refinery & Smelters was dissolved on January 15,1980 after 33 years in business.
As always, anyone have information to add let me know.