Lead Brick Purity

[Hinnerk]

Are lead bricks (see below) generally made of essentially pure lead? I found this one in the second hand shop. It is very easily scratched by fingernail.
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[Dusty Bannister]

Run a cord through the hole and hold it up and tap with a hammer. If it goes "thud" probably very soft lead. If it has a ring to it, not soft. Aside from that, it looks really clean for pure lead which usually will be darker with age and sometimes start to form oxide.

[John Boy]

Drop it on concrete and listen if it goes Clunk. If it goes Clink, it’s not pure Pb

[georgerkahn]

When (50+ years back) I lived on Long Island, NY, I helped a fellow out who ran a recreational sailboat refinishing business/service, and the bottoms of said sailboats often were chock full of similar lead "brick" -- to be used as a counterweight vs the wind caught by sails to propel the vessel. (Bion, when the Mayflower made its voyage to Amerika, its hold was filled with kegs of beer -- the ballast used back then :) )
Anyway -- while I can't compare the SIZE of lead block you have versus the zillions (so it seemed) I took out of to-be-refinished boats, they sure resemble them shape-wise. The consensus then is they were made of lead. Just as Oxygen gas is sold as such (for, say, oxyacetylene welding) AND/OR the guaranteed pure "Medical Grade Oxygen" (for, say, folks with COPD) -- the "grade" lead of the boat brick was "close-enough" to pure to be so labeled.
geo

[lightman]

Most lead bricks are near pure. The holes in yours make me think it was a counterweight and the alloy may be different. Drop a drop of acid on it to test for zinc and scratch it with your thumbnail. If it does not bubble and you can scratch it, call it soft.

[Springfield]

As far as I can remember, every brick like that, with or without holes, has melted down into nice mostly pure lead ingots. The nice thing is that they rarely have much dross when melted also, unlike roof sheeting.

[kevin c]

I talked with a guy at the radiopharmacy where I buy scrapped isotope containers. He told me that one buyer they had before would sell lead bricks for radiation shielding made from the containers, which are ~2.5% Sb per the several analyses I had BNE run for me. Makes sense that if the small containers are a radiation blocking alloy, then bricks of the same can be used the same way.

That being said, the three or four bricks from them that I've melted down were 100% lead, and the metal was clearly different (softer and darker rather than hard and silver) from the containers.