I still STRONGLY doubt the reading by the machine in the OP of 0.9489 silver. I cannot see such a coin ever getting out of the Mint.
By coincidence I received today a copy of the 1859 Assay Commission Report for a story I am working on. In it there are several paragraphs devoted to a single 1858-S Quarter Dollar that assayed out individually at 0.9047 fine, which was above the legal tolerance of 0.9030. As the other San Francisco Mint silver coins assayed individually and in bulk had assayed out much closer to where they should have been, the anomaly was attributed to "...the separation which sometimes occurs between the silver and the alloy in the act of gradual solidification."
They still thought it was a big deal, and went back and tested five additional quarter dollars that has not previously been chosen at random to be fire assayed. Those tested out from 0.8998 to 0.9006, well within tolerance.
So, a slight clumping of silver is possible, but the OP's reading is ten times greater than an assay commission's fire assay result that caused much consternation.
TD
Numismatist. 50 year member ANA. Winner of four ANA Heath Literary Awards; three Wayte and Olga Raymond Literary Awards; Numismatist of the Year Award 2009, and Lifetime Achievement Award 2020. Winner numerous NLG Literary Awards.
@CaptHenway said:
I still STRONGLY doubt the reading by the machine in the OP of 0.9489 silver. I cannot see such a coin ever getting out of the Mint.
By coincidence I received today a copy of the 1859 Assay Commission Report for a story I am working on. In it there are several paragraphs devoted to a single 1858-S Quarter Dollar that assayed out individually at 0.9047 fine, which was above the legal tolerance of 0.9030. As the other San Francisco Mint silver coins assayed individually and in bulk had assayed out much closer to where they should have been, the anomaly was attributed to "...the separation which sometimes occurs between the silver and the alloy in the act of gradual solidification."
They still thought it was a big deal, and went back and tested five additional quarter dollars that has not previously been chosen at random to be fire assayed. Those tested out from 0.8998 to 0.9006, well within tolerance.
So, a slight clumping of silver is possible, but the OP's reading is ten times greater than an assay commission's fire assay result that caused much consternation.
TD
Assay is a bulk property. XRF is a very thin surface layer. That coin if assayed could well measure 0.9000 and the surface measure 0.94. See the earlier science discussion.
Comments
I still STRONGLY doubt the reading by the machine in the OP of 0.9489 silver. I cannot see such a coin ever getting out of the Mint.
By coincidence I received today a copy of the 1859 Assay Commission Report for a story I am working on. In it there are several paragraphs devoted to a single 1858-S Quarter Dollar that assayed out individually at 0.9047 fine, which was above the legal tolerance of 0.9030. As the other San Francisco Mint silver coins assayed individually and in bulk had assayed out much closer to where they should have been, the anomaly was attributed to "...the separation which sometimes occurs between the silver and the alloy in the act of gradual solidification."
They still thought it was a big deal, and went back and tested five additional quarter dollars that has not previously been chosen at random to be fire assayed. Those tested out from 0.8998 to 0.9006, well within tolerance.
So, a slight clumping of silver is possible, but the OP's reading is ten times greater than an assay commission's fire assay result that caused much consternation.
TD
Assay is a bulk property. XRF is a very thin surface layer. That coin if assayed could well measure 0.9000 and the surface measure 0.94. See the earlier science discussion.