yea tosh, it's some kind of low grade iron ore, lots of the stuff around there, a good portion of the rocks have enough iron in them to ring, or even move a compass if you hold it real close.

Oh, yeah, I forgot.

Ah. Interesting. I wonder, what is the Fe₂O₃ percentage, on average?

Hmm, no hands, I wonder if you have a lot of hematite, or magnetite or something. There are a few different iron ores, do you know anything more about it? Oh, and it can be interesting pulling out a compass in some of our lab rooms, with all the different samples around.

im not really sure if it's hematite or magnetite, all i know is its hard as hell, looks like sandstone on the outside and blackish on the inside, and oh yea, the place is on jericho mountain, wich ive heard is an extinct volcano. A piece 3 inches thick stops a steel core 180grain 7.62X54R dead. The stone facade averages about 8 inches thick, so i should be ok for most of what might be incoming.

If you like i can try and find a small sample to send ya, i should be over there this weekend.

http://en.wikipedia.org/wiki/Iron_ore#Magmatic_magnetite_ore_deposits that might be it

I don't know that area at all, and Wikipedia was no help. Don't waste money sending me a rock in the mail ;) but I'd love to see pictures of the area. I've put a lot of geology pictures on DeviantArt (my photography is a Hell of a lot better than my sketching skills....), I love photos of landscapes and geology.

I did find a picture of the mountains on Flickr, and the rocks look sedimentary (I hope it's really a picture of where you're talking about). This is near New Hampshire, right? At first guess I'd imagine the iron is probably cementing the sand together, and is turning yellow as it oxidizes. If it's not in horizontal layers, but looks like it came up and melted through the layers from underneath, then it very well could be magmatic magnetite. Maybe a geologist at whatever university is over there (I don't know the east coast, though I'm probably going there for an internship this coming semester) could tell you what it is.

nah in bucks county pa

Maybe I'll see them. I'm doing an internship in PA area Jan-April.

heres a picture of a section of the wall, crappy camera phone pic at night



the really big rock is about 20 inches across to give a sence of scale, the black on is one that was split in half, heres a really crappy picture of the edge of that



i moved a little as i took the picture, but you can still see the side looks like sandstone. I'll get a better picture some time. in person the black portion looks like some kind of black iron crystal formation, id guess volcanic in nature. a good portion of the rocks once you chip off the outer coating will actually even ring when struck the iron content is high enough.

Ah, your rocks are actually part of a wall, then. Were they quarried locally? Sadly, I can't tell anything from those pictures, sorry. Even good pictures aren't always very good for identifying a rock unless the rock is in-place (where it formed) and the geologist looking at the picture knows something of the geology of the area, which I don't (all I know is western US and a bit about Iceland). Depending on the rock, there are as many as a dozen tests or observations that can be made in the field on a hand sample to identify the rock.

EDIT: Looking at your picture, and how the rock is weathered, it might possibly be basalt with high iron content. Lots of rocks will ring, lots of metals won't, so that's not a conclusive test. Basalt can sometimes weather to a lighter color, and if there's lots of iron I suppose it could oxidize yellow, brown or red, but exposing a fresh surface by splitting it would show the rock's true color, which in the case of basalt is black. Are the crystals visible to the naked eye? If so, is it composed of interlocking crystals that look like they grew together, or are they individual grains cemented together like in sandstone? Is it a uniform color, or are there patterns? If you can see crystals or grains, are they randomly oriented or are they aligned to each other? These clues might help a bit.

i didn't look that closely, and they were all found on the property.

They also very well may have been carried to where you found them by glaciers, I know at a couple points there was two km of ice covering Kansas, and there are a lot of glacial features in that area.

nah this is just south of where the glaciers stopped by just a couple miles actually, it's near newtown pa