Here I am picking up a small cobble of slag at a beach. Since it has been worn by the waves for at least several decades, it looks like a normal, rounded rock.
Picked up. This glass is translucent and comes in two colors, deep purple/gray and dark green.
Looking in chilly Lake Michigan.
Looking for chert near the town of Isabella.
A mix of limestone and chert.
The total haul.
Beach slag on left and center, black slag upper right, and chert far right.
Chert below, slag far left and above.