rock identification

Asked December 2, 2017, 1:43 PM EST

i dont remember where did i get this rock . it seems to excrete some kind of orange mineral , with all my stupidity , i tried to clean it by licking my finger and rubbing the rock , when i went for a second lick a very sour taste came to my mouth , the clear crystals that grow on the rock have a rectanglar shape , some of them have the orange stuff trapped inside . if not the orange stuff the rock whould look like regular granit.
(btw tot really from alaska )

Alaska

1 Response

Hi: It's really very difficult to identify rocks/minerals from photos, and also, without knowing anything about where it comes from - where it was found, because its location can give a lot of information about what it might be (or alternatively, eliminate possibilities)...as an example, if I were to receive a photo of a black rock with the info that someone picked up on Hawaii, I would be able to say with a large degree of certitude that it is basalt (and not likely to be a mudstone or shale).

The yellowish material (it looks more yellowish than orange in your photos) could actually be sulfur - and without knowing anything about where this came from -it's really very hard to say. Typically, based upon your verbal description, without seeing the photos, I would have said it was iron - from weathering. But the pics don't really look like iron-weathering product - and I am not entirely sure that this in fact a rock - it could be a chunk of some type of mineral (many crystals - that would be the clear, rectangular crystals) inter grown with at least one other dark metallic mineral, and possibly a third. This is also very common, especially if this specimen came from an area where there had been active mining (or from a gem/rock shop). In any event, I can't really say what this is. In your first picture, the crystals seem to actually have a hexagonal shape, in which case I would say it is most likely quartz, and the staining is all iron staining. That is the most common (and also most likely) scenario....it is not very common to find sulfur-bearing minerals just lying around. If you live in the Fairbanks area, you can bring it to our statewide office and I can try to ID it for you, or you can also bring it to the state's department of geology and geophysics, or alternatively to the department of geology here at UAF.