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What type of stone is this?

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I've never seen this stone used for a foundation. It looks like bluestone, but I want to make sure. The stone is about four inches thick. It's fairly soft and delaminates easily at the lower courses.The rest of the foundation is brick, brick interior fondation, support piers, etc. The house is from 1903.

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Maybe. I don't know what it is. Shale comes in different colors, but mostly grey. This stuff looks more brown to me.

It could be what's called limey shale, which is shale that's had limestone leach all over it.

Shaling is verbification...........we call that kind of splitting off shaling, it's what the stone mason I worked for called it. Sandstone "shales" different than limestone, different than shale, different than etc......

It looks like shaling sandstone.

Shale is more clay like. When shale, umm.....shales, it's more of a sharp flaky splitting, not so much crumbling.

And, sandstone foundations that get wet and freeze and thaw,...... fall apart.

Like this stuff.

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It's limestone. This type is very common for that period throughout southeastern PA, west-central NJ and I'm sure up into northern NJ. Here's the same limestone in an area of western NJ that I used to hike:


It's not like the limestone Kurt would see in Chicago or would be used in major high-end buildings, which would be Indiana limestone. Indiana is a premium building stone which has a uniform texture and porosity.

Limestone forms a crust on the surface, from weathering and atmospheric pollutants. That's why the faces that haven't flaked off in Neal's pic are a different color from the inside. This crust traps moisture and salts. Once the crust is breached, it flakes off and (relatively) rapid decay begins.

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Was Sandstone ever used on older foundations then? I had thought that the old stuff around here was Sandstone.

Oh yeah, I've seen it used in lots of places around the US and the planet. Hell, most of the 600 year old building foundations in downtown Zweibruecken, Germany are limestone.

When I was first stationed there, I used to walk down the sidewalk and see little piles of powder along those foundation walls. One could brush one's hand over the face of the stonework and the stuff would literally

slough off onto the sidewalk.

Fast forward to May of 1991 when we returned from Iraq and the downtown area and the former Prince's residence at the center of town were undergoing a massive government-funded preservation effort and the Germans had developed some kind of a method to stabilize the stonework and actually restore it. Somehow they'd figured out how to restore those same foundation walls without actually replacing the stones and the work was so good that the stonework looked like those stones had just come from the quarry.

Always wished I'd been there to see what technique they'd used to restore that stuff. I figure they'd probably used a colored concrete technique but never really knew for sure. Whatever it was, it was done well.



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