jgourlay - 16-7-2008 at 14:00
It's chemistry....loosely...
I keep a good supply of rare earth magnets scattered all over hell's half acre because, well, we should. Last night #2 had tossed some on the floor,
and I casually picked them up and set them on the granite countertop. I felt a mild, strange, but unmistakable tug.
So, out of curiosity I let my wife yabber on about something while I tried to see how often the installers had put in a screw. I quickly came to the
unnerving realization that the magnets weren't finding mounting screws. They were attracted to these iridescent black patches in the stone that based
on a appearance I had assumed were mica.
I've seen loadstone magnets, and hematite, but these chunks aren't them. What could this be? The granite is green, the magne-chunks range from .25"
to 1" in nominal sized blobs, and there are gold flecks in the material. The magnetic bits are black with a milky bluish iridescence.
JohnWW - 16-7-2008 at 14:56
Those iridescent black crystals in the polished stone slab are almost certainly magnetite, Fe3O4, which is ferromagnetic. If the stone slab is GREEN,
it certainly would not be granite (or diorite or granodiorite), which is various shades of red, pink, and light to dark grey. The green color is most
likely to indicate an ultra-basic rock composed mainly of Fe(II) and Mg silicates, like peridotite, olivine, dunite, serpentine, fayalite, etc., which
(along with basic rocks like basalt and dolerite) often contains opaque crystals of magnetite. It may possibly be jade, although the latter does not
normally contain crystals of magnetite, or have a macrocrystalline or a porphyritic texture. Do you have a photograph of it?
[Edited on 17-7-08 by JohnWW]
jgourlay - 17-7-2008 at 05:27
I don't but I can get one.
SO!!!!!! If what you are saying is true....this material could basically be used to smelt out high silica Iron!
That of, course, being the holy grail in the search for true, honest to Betsy, wrought iron (as opposed to high purity mild steel).
YT2095 - 18-7-2008 at 01:09
it`s possibly Marble, it comes in Many colors and is popular for kitchen counter tops and bathroom suits etc...
this maybe helpful:
"The characteristic swirls and veins of many colored marble varieties are usually due to various mineral impurities such as clay, silt, sand, IRON
OXIDES, or chert which were originally present as grains or layers in the limestone. Green coloration is often due to serpentine resulting from
originally high magnesium limestone or dolostone with silica impurities. These various impurities have been mobilized and recrystallized by the
intense pressure and heat of the metamorphism."
note the irons oxides I put in caps.
quote taken from: http://en.wikipedia.org/wiki/Marble