This rock was found in a creek and we are unsure what type it is. We know it is magnetic and it is about the size of a basketball. It is run off slag from a smelter. I look forward to hearing your thoughts. There is another rock that may be used by Native Americans and wondered if you could identify that a well?
Thanks for your time,
If it is magnetic, then it contains a fair amount of iron. The only naturally occurring mineral that is magnetic is Magnetite.
Where do you live?
I went to school in Virginia and my family is from the Shenandoah Valley. There were once a lot of iron smelters, they called them furnaces...most of them have women's names because they were built by a father who named them after his daughters. Katherine Furnace...Elizabeth Furnace and so on. They built them near outcrops of ferrous cemented sandstone, limestone, oak trees and a creek. The sandstone supplied the iron ore, the limestone the flux, the oak supplied the carbon charcoal and fuel. Coal was eventually used in place of wood, for fuel, but now you know where a lot of the trees that once covered all those fields in the east went. It took acres and acres of oak to fuel the furnaces. These were pig iron furnaces, big stone towers. When the iron smelted, it separated iron at the bottom, slag at the top. They would run the liquid iron out into a bed of sand, where depressions for ingots had been dug, one central ingot, and smaller ones perpendicular but connected by small channels to the large one, all connected like a mother pig feeding her little piglets. That is where the name pig iron came from. After the ore was run out, they would run out the slag, a greenish glassy looking stuff like "clinker" from a steam engine fire box. What you might have is the stuff from the boundary between the two molten liquids, it contains enough iron to be magnetic, but too much slag to be iron. They would run this stuff into the nearby creek to quench it quickly probably for safety reasons, wouldn't want a bunch of molten slag lying around for someone or an animal to step into.
Send me a picture of the other rock and I'll see what I can do.