12 Affordable and Unusual Gemstones... if you can find them.

[Tourmaline]

7. Chrysocolla in Chalcedony (excluding Arizona Gem Silica)

Arizona Gem Silica is highly prized, but chrysocolla in chalcedony from other sources can be striking, too - but not as highly priced. If you don't have the budget for those neon Paraiba tourmalines, these alternatives are also copper-bearing, and can have the neon glow. In fact, cut en cabochon, they can some look very similar to Paraiba tourmalines! Stones in the photo are from Congo (small glowy ones) and the bigger blues with pseudo malachite inclusions are from Israel.

The ones you thought were from Israel, with the tan dendrites, are now all over the place, currently being marketed as hemimorphite. They are partially delineated glass, not natural stones.

 

[Seaglow]

The ones you thought were from Israel, with the tan dendrites, are now all over the place, currently being marketed as hemimorphite. They are partially delineated glass, not natural stones.

I rechecked with the instruments. According to the GIA Gem ID book, blue glass can have a refractive index of 1.470-1.700 and can go OTL, which compared to Eilat Stone is the same so this is no use. However, blue glass is usually colored by cobalt while Eilat Stone is copper, so spectrum can be checked as well possibly registered color under Chelsea filter. The stones I have, I didn’t see any cobalt spectrum.Registers aggregate under the polariscope. I also checked under the microscope...the dendrites are depressed and not flat like in synthetic turquoise. Also no visible gas bubbles present.

However, there is hemimorphite mineral which is a natural mineral, but it is not included at the GIA Gem ID book under blue stones so I would need to research on this. I checked blue hemimorphite online and apparently, there is a mine (mineral specimens and cabs being sold online) being said to be in Yunnan Province, China.

https://www.minerals.net/mineral/hemimorphite.aspx
http://www.geologypage.com/2014/04/hemimorphite.html

 

[Seaglow]

Shangrila Gems at a gem auction site are selling the ones with the light dendrites in a gem auction site and also gemselect on their site.

But I also am not surprised if it turns to be imitated in a jiffy. I remember buying translucent amazonite beads with @Bluegemz of which a sample was sent to GIA with the result as Amazonite with Luster Enhancement (most likely waxing) then very shortly some impregnated amazonite beads lwere reported by GIA hitting the market.

 

[Seaglow]

I just read the summer of 2012 for Gems and Gemology on an article regarding Partially Devitrified Glass Imitation of Hemimorphite which says that microscope reveals “radiating clusters of fine blade-like crystals that formed a fibrous texture, along with randomly distributed clusters of white dendritic inclusions”. GIA used Raman analysis to conclude devitrified glass and to separate from chrysocolla from hemimorphite, one can check the specific gravity. I don’t have a hydrostatic SG scale though at the moment....

So the stimulants have existed for quite long (spotted around 2010 according to the article). The inclusions in the stones I have are not white. Just for fun, here are the magnified photos and maybe one day someone with more knowledge may stumble here and know what they are!



Under reflected light, the inclusions have surface depression.

 

[Anne111]

WOW! Thanks. What a trip!

 

[Tourmaline]

How about temperature? Does it feel cold like quartz, or room temperature like glass? I have a couple of pieces and they were under $10. They were sold as hemimorphite, but I assumed they were fake before I got them. Real hemimorphite looks nothing like it. They’re very pretty, though.

I came to this thread the other day because I have been researching natural blue chalcedony/gem silica lately, because I’ve just purchased some that seems too good to be true. I’ll be sending it to GIA soon.

 

[Seaglow]

How about temperature? Does it feel cold like quartz, or room temperature like glass? I have a couple of pieces and they were under $10. They were sold as hemimorphite, but I assumed they were fake before I got them. Real hemimorphite looks nothing like it. They’re very pretty, though.

I came to this thread the other day because I have been researching natural blue chalcedony/gem silica lately, because I’ve just purchased some that seems too good to be true. I’ll be sending it to GIA soon.

I paid more than $10 for each but below $100 and sold as chrysocolla from Israel.

I checked with the Presidium tester for thermal conductivity and it registers slightly above glass at tourmaline level. I also tested some Arizona gem silica which tests at jadeite area, and a chrysocolla in matrix carving from Congo which registers differently per spot (anywhere from tourmaline level to jadeite level, the gray patches registers higher than the blue). I saw a fracture at the base of one of the stones and the fracture is not vitreous which is the nature of glass. The fracture luster is waxy to dull.

Attaching photos of the thermal conductivity estimates of Presidium as well as the fracture luster under the reflected light in the microscope and my chrysocolla in matrix carving that I tested for thermal conductivity.

 

[Tourmaline]

Interesting! I have also seen it in a darker blue, sold as Lazulite, though man-made and having nothing in common with natural Lazulite, and the manmade version has been compared in a mineral enthusiasts' group to Victoria stone, which is man-made, too.



If you do an eBay search for "hemimorphite cabochon" you will see around 50 stones that look to be the same material as yours.

 

[Seaglow]

Interesting! I have also seen it in a darker blue, sold as Lazulite, though man-made and having nothing in common with natural Lazulite, and the manmade version has been compared in a mineral enthusiasts' group to Victoria stone, which is man-made, too.



If you do an eBay search for "hemimorphite cabochon" you will see around 50 stones that look to be the same material as yours.

For sure there is devitrified glass with dendritic inclusions as reported by GIA. Did you buy the stuff? Do you have a photo of the one you are sending to the lab? Maybe you can also check under a loupe with reflected light? I am curious myself. They look similar but I cannot tell unless I look under the microscope. Not sure what I have conclusively as it requires lab testing with more sophisticated equipment.

 

[Seaglow]

So I saw this article and it shows the crystals in devitrified glass...the samples I have does not have these crystals at 64x....but I also cannot see any botryoidal structure.... I think further lab testing needed for a more accurate conclusion since dendrites occur in devitrified glass, natural chalcedony, and opals.

https://www.gem-passion.com/glass-crystalline-inclusions

 

[Tourmaline]

No, the blue chalcedony I am sending to GIA is totally unrelated to this stone. It was just the reason I searched for this thread. I remembered the chrysocolla in chalcedony.

 

[PieAreSquared]

Thanks @hathien1102 for bumping this post, I totally missed it in 2018!
Fascinating @Seaglow thanks for the tour!

 

[Ella]

Closing this as it is an old thread that a spammer resurrected.