Mudlarking 90

[squirmelia]

There were a few other mudlarks on the foreshore at low tide, and I was late, so felt like I'd missed all the good things.

But! I did solve the mystery of my previous find, which people had guessed was grapeshot or milling balls or sheep poo! It's kind of concretey, and the concrete must have broken away, leaving just the balls.

There were crab legs on the shore which made me sad.

I found a few tiny pieces of Westerwald.



(You need a permit to search or mudlark on the Thames foreshore.)

Comments

[spiralsheep]

https://en.wikipedia.org/wiki/Ground_granulated_blast-furnace_slag#Applications

:-)

[squirmelia]

Ooh, looks like the right stuff!

[spiralsheep]

I don't know if it's exactly that process but looks like similar materials: high temperature slag; and the same again + very pale cement. Certainly another interesting urbanite. Industrial byproducts such as slags are endlessly varied and interesting but often difficult to identify or date without a portable xrf machine.

[squirmelia]

Do you think it does make sense that this one either lost the cement bit, or something went wrong in the process and it all got stuck together?

[spiralsheep]

I would guess your first find is a byproduct from the blast furnace as it's delivered to the cement factory. Easy for that to end up in the river. I suspect the ball + cement mix is accidental and the two raw materials have been mixed in an overspill, but there might also be a use for the coarser ball + cement concrete that I'm wholly unaware of so it could be a deliberate mix. I dunno, it's a bit recent for me!

[spiralsheep]

I'd also like to heft the balls to feel the weight and see the texture under a hand lens before declaring it definitely blast furnace slag (other slags are available!) - I found a weird melted ceramic + glass rod in the estuary of the River Dee years ago and it's been examind by actual experts and they didn't know what it was either!