Blue and green rock ID help please

[carloscinco]

I bought this rock and several others a few months ago from a fella who had bought some rocks at an estate sale, had no idea what they were but figured he might sell them to someone who did. Wrong.


I knocked a piece off and the rock seems to break along the blue lines which makes it look like a breccia that healed the cracks with this blue material (maybe chrysocolla?). You can see it's got some iron in it.

I tumbled a piece all the way through the polish step but it's too soft although it had a few shiny spots.Maybe it should be polished on wheels instead.

What iz it? Thanks for your advice in advance.

[deb193redux]

I was going to suggest plasma agate until I saw the last pic ... don't know

[wardrums]

Maybe a malachite mix of something?

[Deleted]

scratches with a pocket knife??

[carloscinco]

Yes, it can be scratched with a pocket knife.

[vegasjames]

Looks a lot like the variscite I collect. Variscite generally has a hardness of 4-5, although the variscite in some places have a higher silica content making it much harder and more stable.

Variscite is generally various shades of green running from bright, light green to dark emerald green. It an also be found in some other colors such as red. From what I have read most variscite needs stabilization just like turquoise, which is its relative. Both turquoise and variscite have the same basic composition. But turquoise contains copper as where variscite does not. They often occur together in which the stone is referred to as "variquoise".

Variscite is graded just like turquoise. Light green variscite generally runs around $0.50 per gram. As the green color darkens the price goes up. Dark green variscite is considered the most valuable selling for $9-10 per gram on average.

Here are a few pieces I did recently practicing how to cab:





If I get chance later today I will try to get some pics of the raw stuff I just collected including my prize 91 pounder.

[vegasjames]

I got a few pics of some of my pieces of variscite:



This was the largest chunk I found. It is 91 pound piece of blue-green variscite:

[Deleted]

holy smokes batman! Thatsa big variscite.

[vegasjames]

Take away the cigarette and that's almost what I looked like carrying it back to the truck.

[tandl]

i was thinking variscite . the brain often tells the smoker to light up just before picking up a large rock and carrying it uphill .

[bjurney]

Im trying to figure out why someone would wear a Batman suit while rockhounding.... I agree, the top two pics do look like variscite to me and based on the colors maybe from the Little Green Monster Mine (yes its an actual place). The other two pics look different though, almost bluish, maybe its the lighting, are they the same rock?

[vegasjames]

Jul 26, 2013 16:23:25 GMT -5 bjurney said:

Im trying to figure out why someone would wear a Batman suit while rockhounding....

Because if you dress up as Robin instead you will get your butt kicked by the other rockhounders.

[jakesrocks]

It may contain a little variscite, but it appears to be a copper mineral mixture. Variscite is Mohs 3-1/2 to 4-1/2.

Images for Variscite. www.google.com/search?q=variscite&biw=1280&bih=528&sei=mxDzUbzYF8SbygG5yIHADA&tbm=isch

This is variscite.

[carloscinco]

All four pix are of the same rock. The third pix show the color of the material on freshly revealed surfaces after breaking the rock and the fourth pic shows the material after the polishing step in the tumbler. The surface in the third pic is mostly blueish green with some dark blue speckles. The colors are very true to the real color of the rock. I have a large chunk of variscite and it is very similar in coloration to the second picture in Jakesrocks posting without the crust.

[jakesrocks]

I don't have my photo lights set up. The first pic looks yellowish, but both pics are the same rock. Utah material that I've had laying around since the late 80's or early 90's.

[vegasjames]

Jul 26, 2013 18:50:12 GMT -5 jakesrocks said:

It may contain a little variscite, but it appears to be a copper mineral mixture. Variscite is Mohs 3-1/2 to 4-1/2.

Depends on the variscite.  Just like turquoise, which it is almost identical to most variscite needs to be stabilized.  But the variscite, like most of the turquoise in Nevada has a higher silica content making is much harder and more stable that most of the turquoise and variscite found elsewhere.  I have heard the variscite in Northern Nevada for example is quite hard.  And the variscite I have collected is definitely harder than 4 1/2.  Tough as well.  I have been slamming the big piece I have with a small sledge hammer and have only managed to knock off maybe 5 pounds.  The deposits I found were just as bad.  I kept smacking the stuff hard with a rock hammer and barely made a dent.  So I stuck to collecting the loose pieces.

[jakesrocks]

As I said before, that stuff may contain some Variscite, but it's basically a mixture of copper minerals. When in doubt, check the real authority, Mindat. www.mindat.org/

[orrum]

Hey Jake, I kmow Jakes is the dog but I forgot ur name. I agree I have a bunch of Lucin varisite, its sof rf and hard in the same piece. I slab it thick, like 1/4 inch or better nd sorta crumble the edges off with my fingers and then back it with Devcon. It cabs nice usually, just use a light touch. It takes a decent shine with Zam and has a light tan matrix in some. Its a real light fairly uniform shade of green. I have gotten it from several people and it all serms to work good. Some has a streak or thin vein of real gemmy vibrant green thru it. I dont think you could saw a cab from it without getting the soft light green in it. I like soft rocks.

[vegasjames]

Jul 27, 2013 8:56:04 GMT -5 jakesrocks said:

As I said before, that stuff may contain some Variscite, but it's basically a mixture of copper minerals. When in doubt, check the real authority, Mindat. www.mindat.org/

And once again, the hardness can exceed 4 1/2 just like its almost identical cousin turquoise:

nevada-outback-gems.com/turq_info_pages/Turquoise_inf_minfact.htm

For those not really familiar with turquoise or variscite here is some basic information. Both are formed by the deposition of phosphate and aluminum salts, which also means that the hardness will depend in large part what minerals these salts deposit in to.  These salts act as a cement within these other stones, which can include apatite (hardness 5) and quartzite (hardness 7).  Being that there are so many types of stone in which turquoise or variscite can form we cannot state that all the turquoise and variscite in the world will fall with a narrow hardness range. 

In fact, I found an analysis for a sample of variscite.  It was 22.68% water, 44.73% phosphorus trioxide, traces of iron, chromium and vanadium and 32.4% aluminum oxide.  Since everyone here is not familiar with the hardness of various stone, aluminum oxide corundum) itself has a hardness of 9.

And as I pointed out earlier much of the variscite here in Nevada has a higher silica content, which by the way quartzite is silica, increasing the hardness of the variscite.  This is why when most variscite is considered softer than turquoise and does not wear well much of the variscite from Nevada can be more durable than most turquoise.  And again, turquoise also varies in hardness.  Yet is does not matter if the silica or aluminum oxide content in turquoise is 1% or 40%, it is still turquoise.

Now, I am going to make another comparison to another mineral to show a point. Opals can also vary in hardness depending on several factors.  Their amount of water and their amount of aluminum oxide.  The less water and the more aluminum oxide they contain the harder the material becomes.  If all the water is lost from the opal the opal becomes chalcedony with a hardness.  Mindat lists the hardness of opal at 5 1/12 to 6 1/2 and chalcedony from 6 1/2 to 7.  A similar hardening process can occur with the dehydration of variscite.  One study showed that changes in variscite could be made at below 160F, which not only induces dehydration of the variscite but can also alter the color changing some of the green variscite in to a more lavender variscite.  The lower deserts do get more than hot enough to induce these changes in variscite and I have seen this in the variscite I have collected.

On the other hand if Jakesrocks want to really argue technicalities it could be pointed out that the loss of water from variscite (AlPO₄.2H₂O) means it is no longer variscite, but rather berlinite (AlPO4), with a hardness of 7, which is well above the hardness he claims.  On the other hand since the berlinite is only going to be a partial component of the alteration of some of the variscite increasing the hardness of the variscite we are still going to refer to it as variscite unless there has been a 100% loss of water.  Just like we call opal with a 24% water content opal.  As it starts losing water content though we don't call it chalcedony just because it is heading in that direction.  The opal still has to lose sufficient water for the mineral name to change from opal to chalcedony.

When in doubt try actually researching the subject so you know what you are talking about.

[jakesrocks]

And I say, Don't be a know it all. By trying to be one, you'll find yourself loosing the few friends you have on here.
Try the real experts at Mindat. You can get all sorts of conflicting info by googling. Different dealers and mine owners will make all sorts of claims about their material.
I do my research. I trust the experts at Mindat. Folks with more combined years of research and actually doing chemical analysis of specimens than you, me and half of the not so know it all members on this forum.

I don't claim to know all of the answers. If I'm wrong in giving an answer, I'll be the first to admit it. It's obvious that you can't and won't do the same. You, the great Googlemiester know all.