FMF - Friends of Minerals Forum, discussion and message board

[quigi]

These crystals were found in the same area as the one I posted under the topic I posted here https://www.mineral-forum.com/message-board/viewtopic.php?t=6502 on the northern shores of Lake Erie.

I've removed the matrix and now that I have a dual SW/LW UV I decided to check them out.

From what I understand, garnet and ruby don't form in the same matrix and garnet doesn't fluoresce like a ruby, so I'm a bit confused with these results.

Any thoughts?

Thanks!

[John Betts]

Zircon and corundum (ruby) do occur together. Zircon frequently fluoresces yellow though.

It would be helpful if you could perform scratch test. Corundum is hard and will scratch topaz and beryl.

[Joseph McAnney]

It looks like the matrix is fluorescing red. Feldspar can fluoresce red and garnet occurs in feldspar.

[quigi]

[quigi]

[Bob Carnein]

I agree with Joseph. Apparently, the garnet (?) is partly surrounded by light colored material that is fluorescing, and that could be microcline.

[Josele]

Fluorescence color alone is not a definitive way to recognize mineral species. White stuff fluorescing red could be also calcite.
In other hand, feldspar with red fluorescence use to be plagioclase more than microcline.
I think in this case hardness is a more reliable way to distinguish between garnet and corundum. Try to scratch a piece of beryl or topaz, which will be scratched by corundum but not by garnet.

[Bob Carnein]

That's true, of course, and it illustrates why this kind of discussion isn't very useful without more information.