Another Mystery Ingot Question

[fourarmed]

A friend has some ingots that he would like to know about. These are commercial ingots of around 5 lbs, marked S-G. They are quite hard. I ran a ball-bearing test using one of my soft lead ingots, and estimate the hardness as 21+/-2. The tab where it was broken off from another ingot shows bright specks surrounded by darker matrix.

[Doby45]

bright specks surrounded by darker matrix.

http://i33.tinypic.com/59uc15.jpg

[runfiverun]

with a large crystalline structure and a straight break.
that'd indicate linotype or a mix of mono-stereo-lino.
the bhn after casting and waiting is a good indication of lino.