Limonite Goethite psuedomorph after Pyrite with Chrysocolla?

[Steve1236]

Finally got back out to that spot with the chrysocolla, the last big storm completely changed the tributary so I had no idea where to dig, I found a couple specimens but not really anything for lapidary, first one I think is a psuedomorph? Worst thing is I forgot to bring a spray bottle to see what I was digging up so when I thought I scored I ended up carrying out 50 plus pounds of worthless ugly ore, the last two pictured lol, I'll post what I found...

 

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[fuss]

Nice, wish I had a day out there to poke around.

 

[Steve1236]

Need a little help on the correct name, the blue wont scratch with a steel knife so I'm thinking gem silica? The matrix/host is like sandstone, crumbly if you see a crack, quartzite I'm thinking maybe? Would gem silica in quartzite be the correct terminology?

 

[DDancer]

Chrysocolla in sugar quartz is what I'd call it. Quarztite is very solid material usually with no visible crystal structure, sugar quartz is a matrix of fine quartz crystals that breaks easily and has a grainy texture.

 

[Steve1236]

Oh ok, on the chrysocolla, are you sure it's not gem silica? Its harder than the sugar quartz stuff, I wasn't able to scratch it with a steel knife, the other chrysocolla from out there scratches easily with the same knife.

 

[Steve1236]

I just now took a broken sharp piece of chalcedony from out at my fire agate spot and it also would not scratch the aqua blue so it's a chrysocolla silicate which I thought is what gem silica is?

 

[fuss]

It does not look like a quartzite to me either, I'd go with what Dancer said. Now whether that is chalcedony (gem silica) on the quartz or standard crystaline quartz with chrysacolla/copper coloration I cant tell from the images. Nice color though on that rock.

 

[Steve1236]

Thanks for your guys help fuss and DDancer here's some close up shots of the blue, it looks like what other people are calling gem silica online but that's why I ask on here first, people really get pissed when you miss label something, even when you ask a fraction of what others ask, kind of takes the fun out of all of it when someone gets pissy lol..

 

[DDancer]

Gem silica is a broad name so if you want you can use it to describe just about any gemmy material. Copper infused silicates can come in various hardness, the harder and more colorful the better. Take Turquoise for instance. Low grade its very soft and not used as a gem but the higher the silicate content the harder it is and the more useful it is for cutting and shaping. Coloration is also important for Turquoise as well so it can be called a Gem Silica depending on the grade.

 

[Clay Diggins]

Turquoise is a hydrated phosphate of copper and aluminum. There is no silica in turquoise but it is sometimes found in association with quartz.

There are a lot of green/blue copper minerals. Real turquoise is rare but a lot of green/blue silicates and carbonates get passed off as turquoise.

The copper minerals, with the exception of well crystallized Azurite, Malachite and native copper, are virtually impossible to distinguish by sight alone. Being a secondary mineral Chrysocolla doesn't have any crystal structure of it's own but it does incorporate silica as a minor part of it's chemical makeup.

The appearance and color of your rock (mineral?) very closely resembles natural Chrysocolla. It doesn't look like any gem silica I've handled.

The copper group has a lot of different minerals often found in close association. Color is often used unsuccessfully to identify minerals in this group but hardness is a much better indicator. For example Turquoise and Gem Silica both have hardness around 5 - 6.5. They are borderline semiprecious stones - just barely hard enough to be worn in jewelry with care. Chrysocolla, Azurite, Malachite and the vast majority of the other copper colored minerals have hardness of 2 - 3.5 and don't wear well in jewelry.

I suggest you add a good set of hardness picks to your kit if you are going to be collecting rocks and minerals in the copper rich areas. Here's my preferred set which includes Mohs 2-9 hardness picks, multiple streak plates, magnet and a table of 300 mineral's hardness in a compact set. Good for the field or lab. There are many more hardness picks to choose from but buyer beware quality and hardness ranges vary considerably.

 

[DDancer]

I stand corrected, never bothered to look up what defines gem silica as I always thought it was a generic term. Turquoise I thought was impressed with silicates and again I'm corrected, seems there is some wonder in the world besides were one finds things and make's associations. Hehh. Thanks Clay.

 

[Steve1236]

Youd probably have to stabilize it because the sugar quartz doesn't hold up well so probably not worth anything to anyone I'll probably just put it in the garden area but very hard chrysocolla it is since a sharp piece of quartz would not scratch the chrysocolla, thanks everyone.