White Pine Copper Mine, Old Cast Copper Ingot for Assay, 8 Lbs

Description

This is an unmarked cast copper ingot made at the former White Pine copper mine at White Pine, Michigan.
This type of ingot was made when copper was being poured from the converter and again from the reverberatory, to be tested for oxygen content; you can see that six holes were drilled into it to remove copper for assaying.
It weighs about 8 pounds and measures about 2-1/2 inches by 7-1/4 inches and is 1-3/4 inches thick.
I only wiped it off with soapy water and a rag; some people clean them off with dilute acid and a wire brush to remove the oxidation.
These were being poured up until 1982 when the mine began producing pure copper by the electrolytic process.
I have only seen a few of these with these test holes.
See page 38 of my book for pictures and information,
White Pine Copper: An Illustrated History of the Mine and Its Ingots.
This book is available from my ebay store.
The White Pine mine produced over 4 billion pounds of copper and 45 million ounces of silver from 1955 to 1995.
Shipped by padded flat rate envelope.
If you buy more than one lot in my sale, I will reduce the postage, but please wait for the combined shipping invoice before you pay.
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