I was walking behind the yard after backingfilling a drain pipe and remembering the days when I was young(er) looking at the train tracks.. looked down and saw this..

A small fridge magnet will lightly attract to it so it must have some amount of iron in it - probably not enough to mess around with. Wondering what it is from though. Possibly from the coal burning locomotive days?

Anyhoo. just thought I'd share. Love the forum!

Several folks have brought strange rocks found along RR tracks to hammer-ins, they turned out to be sprues from thermit welding. They looked more grainy than yours, though.

Good point. I did think of that before but the tracks here are bolted together. It may have been possible the rails were changed at one point but I doubt it. It may have been in the loads of rail rock that they spread around so it may not even be native to here but frome somewhere where thermite was used. I'll have to go meander about some more.

looks like a piece of bog iron, at one time bog iron was the primary source of iron ore for wrought iron.

That looks like big a clinker of impurities. trains, ship, foundries and large boilers use to burn large coal of any grade. My grandfather was a steamship captain so he would always point out stuff to me that had to do with steam power plants. I have also found those on train tracks and when I have done excavation around old houses that had old coal boilers and all around in the ground at the site of an old factory blacksmith shop that I was running underground utilities to. It should almost break glass like when hit with a hammer. Thermite track welding slage tends to not break with a hammer.

yeah. .some form of iron ore. .probly fell off a transport. .

the coal ash and clinkers used to fall out the bottom of the firebox into the center of the tracks, most likely a clinker from a steam locomotive. Old round house repair shops here had stacks of them around.

rail beds where often made with blast furnace slag
there are several beds locally that you can still see the slag where the subsequent gravel overlays have moved.

What Ice said, it's blast furnace slag used for the rail beds up near the furnaces.

It does NOT look like bog iron---too vesicular though bog iron is often nodular.

This double topic has been split into two threads.
The Iron supply thread - click here

The "ballast" used on Metrolinks railroad bed is iron ore slag, or so I am told. I don't know why other than what I was told, "it is cheap". It does not look like what you have pictured although it may be related. It is actually a bad choice for electric train track ballast due to it being conductive and easily ground up into a fine dust. The dust literally coats every electrical componenet on the trains and is a major mess to deal with. Our ballast is a reddish brown color that is flaked and chipped into gravel size chunks, some of it is pourous like lava rock.