Gem silica

My poor retinas! I do NOT recommend doing this!!!

the work light shows the translucent areas better. Looks green in the pic but the corner on the right normally looks blue. think that is the purest blue area but hard to tell how large it is.

I had some material similar to that stuff once. In particular the bottom right of the first pic makes amazing cabs that take a nice glossy polish due to the high silica content.

Regarding which saw to use, for a stone that size I would use my 14" slab saw. I *think my 10" could manage it but that is larger than I like to cut with a trim saw. You would have to accept that you'll lose some of the material but you'll lose some regardless, imo I would just use my slab saw for ease of operation.

Haven't heard of the inspiration mine but the gem silica I had that looked similar was supposedly from Peru.

Btw it’s entirely possible that I am misunderstanding what I am looking at! I honestly thought this was some weird man made rock when I found it (thank you to those of you that told me otherwise!) so all I know about gem silica is what I’ve gleaned through a lot of searches and YouTube. 

if I’m doing the light test wrong or misinterpreting what I am seeing, someone please tell me! First two pics are some of the more gemmy offcuts.





these are some of the lesser ones, what the majority of pieces are 

Is the gem silica not worth thinking about unless it’s larger, pure pieces? Hard to get good pics of it (can try outside later, and actually wet it this time!) but there’s an area that has a pretty hefty amount of gem silica in it. If I was aiming for PURE pieces without inclusions those would end up fairly small. The off cuts seem to have been taken off of the larger faces while the gem silica goes deeper, so not a lot visible in those.

That is a beauty, I wish it was in my collection. There is no way I would cut it, you could not replace it.

SLAB THE CRAP OUTTA THAT PIECE!!


There's a cab I made from that same material in this thread:


forum.rocktumblinghobby.com/thread/105993/got-cabochons-week-28-24

cabby I'm not sure what to tell you regarding slabbing it but I can tell you this....

While an unpopular opinion im sure, I run my 14" slab saw with "gem lube" from kingsley. It is an additive type coolant, mix 1 part gem lube to 10 parts water. I haven't noticed any problems with using it. But I tend to not do everything as stated as popular opinion. I try and see for myself. In fact I've been advocating the cheap kingsley notched blades as well. I've had the same notched blade in my 14" saw now it will be a year in October. It cuts just fine!

Regarding the gemmiest of gem sections I would suppose you'll have a hard time isolating and extracting just that. Honestly though unless you have a customer who commissioned a piece requesting it I would keep the inclusions in the piece. I personally love the interplay of the malachite/chrysocolla/silica sections!

But I can understand you wanting a (small) cab of the purest stuff! I have a piece of gem chrysoprase that I paid $1/gram way back around 2000 when I first got interested in lapidary. The guy (who was not wrong) selling it told me its incredibly hard to find stuff that gemmy. Years later and taking a close look at it even at A grade a it has some veiling (inclusions).I would have to suppose a piece with zero inclusions wouldbe considered AAA grade!

I'm gonna have to do some deep digging, I know I took a picture of one of the cabs I made of the gem silica I had...I feel like the cab itself is around somewhere as well but where is anyone's guess. Thats what happens when you're short on space and long on rocks

I'll reply if I can find it!

lapidary1234 WOW! Thank you so much for the pics! It’s super useful seeing what others have done with similar material since Google search only wants to show me the cream of the crop or listings. I kept rereading the price you paid for chrysoprase… yikes! This guy had very few gemstone type things, just some coober pedy opals and a yet unidentified tiny something (swear I will figure it out someday), so I haven’t been thinking in gemstone prices yet! Been having a hard enough time figuring out the darn slabs lol.

Knew gem silica is valuable so figured it might be worth isolating, but no clue what the prices would be. The gemmy areas would be more like the final pic you showed, wouldn’t be able to avoid small opaque areas (crysocolla or malachite in this case, no host on this rough) or at least sections of uncolored chalcedony in each cut stone. The videos I’ve seen treat gem silica more like gemstones, grinding away at a chunk to find the best bit vs preform from slab, so no clue how I would even cut or sell this! With all of the malachite and chrysocolla bits I guess this is cabbing grade, not faceting. The entire rock is 960g with the mostly gemmy area being probably 200-250g? So if working from slabs could get a fair number of cabs like last pic, and quite possibly a few that size pure gem silica, but won’t know until I try isolating it. The rest of the rough is so large that I can’t get a good look at it.

As fun as it is to look through these things, I’m starting to get a bit sick of rough that is so rare these days that I can’t find comparable products online 😆

victor1941 those are beautiful!! Thank you for sharing those. While it may not be as premium as pure gem silica, your examples show that the inclusions make for beautiful material as well! Personally, I think I prefer the inclusions more than pure gem silica!