Identity HelpUnknown Green and White Mineral from Guatemala Highlands
New specimen I found yesterday!
Found in Chiantla in the highlands of Guatemala (up in the Cuchumatantes Mountains).
This was found in an old dried up river bed.
The specimen itself is various colors of Green, some sections appearing semi-transparent.
It scratches easily with steel. The material itself will also leave a scratch mark on glass. It does not appear to scratch with fingernail.
The white material is quite brittle and looks like it has dendrites on it. I thought Chacedony at first, but it scratches quite easily and is pretty brittle. It is found throughout the entire matrix of the largest piece of this I found. One of the photos shows the light easily passing through a small specimen.
Any chance it is Dendritic opal? And any way to test for Opal?
this shot showed some nice cleavage, thought it would help a lot with an I.D.that was my guess. I've found lots of Serpentine on other rocks and minerals, but never a huge piece of all Serpentine.
Could the white be Serpentine too? Or would it be something else? Opalized Serpentine? 
Hardness test is a bit confusing where you wrote "It scratches easily with steel. The material itself will also leave a scratch mark on glass.". Glass is slightly harder than steel so did you mean the reverse? The rock also looks like a mineral mixture so the hardness can vary a lot depending on where the test is taken. If it scratches glass then likely there has been siliceous alteration possibly forming Chalcedony or silica replacement of the serpentine. The first picture has the texture of slickensides indicating faulting and shearing of the rock providing an avenue for alteration. 
I agree.
This specimen seems to be a mixture of at least a few different things which could potentially give different hardness results. It also seems from the photos that you're probably dealing with a couple different periods of mineral formation; the original rock, then a crust of some sort that formed over. It's going to be quite difficult to accurately determine what you have Robert without actually seeing the specimen in person. Who wants to see some stuff in person?!
I'm coming to the states the end of this month.
I'll mail a bunch of samples I have been finding if any one if interested.
