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ROCKS!

pitw

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It has "remarkable clarity and a perfectly balanced golden green hue," the statement said.
Is it just me or does that look like something man[type] made?
 

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Hypophthalmichthys molitrix
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I was looking at that myself pity. These are what yer talking about?

Emerald.jpg

Let me do a little research on emerald building

BF
 

Unca Walt

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Save your time. Us rock-houndish types can recognize natural crystal structure from fitty feet away.

Here's a really nice emerald in matrix. If you ever want to see "man-made-lookie", here 'tis:





This ain't as sexy... well mebbe it is, considering each "stepping post" is two feets across. Sauce: It's basalt.



Oh, dear... my trivia dingle got dingled: Basalt has a peculiar quality: It makes sooper soundproofing in this state. Tricky to put in the back of your pickup, though.
 

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In its pure state beryl is a colorless mediocre mineral. But impurities in its makeup give it a beautiful range of colors. Its color ranges from pale, peachy yellow, to blues, reds and greens. The presence of iron produces the blues of aquamarine and the yellow of heliodor, while manganese gives rise to the pink of morganite and the extremely rare red beryl. Chromium and vanadium creates the brilliant green of emerald.

The emerald has been prized for millennia, the ancient Egyptians mined emeralds as early as 3000 BC. The gem is prized in the Vedas, the sacred texts of Hinduism. The Aztecs and the Incas both worshiped the stone. The Romans associated the stone with love, dedicating the color green to Venus, the goddess of love.

Hardness is 7½ to 8, streak is white, specific gravity is 2.6 – 2.8, luster is vitreous, chemical formula is Be3Al2Si6018, and crystal structure is hexagonal. Here are a few examples of the green beryl, referred to as emerald.


Carnaiba emerald.jpg
The Carnaiba emerald weighs 794 pounds discovered August 2017 at the Carnaiba Mine in Brazil
Devonshire Emerald.jpg
The Duke of Devonshire Emerald 1,383.95 carats sold to William Cavendish, in 1831.
Gachala emerald.jpg
The Gachala emerald 858 carats discovered in 1967 at the Vega de San Juan mine in Columbia.
La Gloria Emerald.jpg
The La Gloria Emerald 887 Carats found in the wreck of the Nuestra Señora de Atocha shipwreck in 1985
Patricia Emerald.jpg
The Patricia Emerald 632 carats Found in Colombia in 1920
The Bahia Emerald.jpg
Bahia Mineral Cooperative emerald weighs about 600 pounds discovered May 2017 at the Bahia Mine in Brazil

Not withstanding walter's prognostications, this rock fuddy-duddy has to get within 15 inches of any mineral to even begin to figure out what it might be. Except for the last one there, I might be able to discern it's identity from 40 - 50 feet. :Happy:

BF
PS: 155.5174 carats to one troy ounce
 
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Green agate? Are you sure it's not jade or nephrite?
You must have been rock hounding in an area that had lots of trace copper.

BF
 

EricTheCat

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There are a number of copper sources in the general area. There is also a very large amount of quartz in many forms such as agate, chert, flint, jasper etc. My hunch is the specimen is quartz based. I could be wrong but I don't think jade or nephrite are found in that area. Given the similarity in hardness (6.5 vs 7) it could actually be difficult to say for sure.
 

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Man, tough to — id agate & jade are pretty close in everything; SG: j 3.2-3.4, a 2.7; streak: j white, a white; hardness; j 6-7, a 7; luster: j virt to greasy, a virt to waxy; and the color range about the same for both minerals. Did notice one major difference, though, on fracture (as in breaking the stone heh) agate will break off flakes (Conchoidal fractures) while jade will cleave or shatter. Agate does not cleave.

So how good are you with specific gravity?

BF
 

newmisty

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Man, tough to — id agate & jade are pretty close in everything; SG: j 3.2-3.4, a 2.7; streak: j white, a white; hardness; j 6-7, a 7; luster: j virt to greasy, a virt to waxy; and the color range about the same for both minerals. Did notice one major difference, though, on fracture (as in breaking the stone heh) agate will break off flakes (Conchoidal fractures) while jade will cleave or shatter. Agate does not cleave.

So how good are you with specific gravity?

BF
What's virt?
 

GOLDBRIX

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The Kapeta emerald is indeed a natural stone and not synthetic.
That is the "tell" in gems. If it appears too perfect there is an excellent chance it is man-made.
 

GOLDBRIX

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That is the "tell" in gems. If it appears too perfect there is an excellent chance it is man-made.
I just found this thread. Others may have already addressed this.
 

EricTheCat

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Man, tough to — id agate & jade are pretty close in everything; SG: j 3.2-3.4, a 2.7; streak: j white, a white; hardness; j 6-7, a 7; luster: j virt to greasy, a virt to waxy; and the color range about the same for both minerals. Did notice one major difference, though, on fracture (as in breaking the stone heh) agate will break off flakes (Conchoidal fractures) while jade will cleave or shatter. Agate does not cleave.

So how good are you with specific gravity?

BF
Specific gravity would probably be the way to know for certain. Perhaps I'll try that one of these days. One thing I will add, if you look above the quarter in my 2nd pic of the rocks there is an example of what appears to be the same green mineral and it is in matrix indicating it formed much the same way as an agate in basalt and it is sedimentary.
 
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Hypophthalmichthys molitrix
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There’s properties geologist (or some intelligentsia group) assigns rocks. There’s; Group, Crystal system, Composition (chemical), Color, Form , Hardness, Cleavage (no jokes, now), Fracture, Luster, Streak, Specific Gravity, and Transparency.

About “virt” — it was my shorthand for vitreous What I really meant was “Vitr” — twisted fingers. My bad.
And you use a streak plate just like the one you use to get a streak for an acid test on Au. And if you expect green jade to leave a green streak, it won't.

BF
 

Unca Walt

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...it formed much the same way as an agate in basalt and it is sedentary.
(*snork*) I don't check spellings here, but you just used one of my one-liners.

When I haveta go see a doctor and he tells me to exercise more, I tell him I will try not to be sedimentary anymore. ;)
 

newmisty

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I thought most all rocks were sedentary in nature lest they succumb to an avalanche.
 

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I thought most all rocks were sedentary in nature lest they succumb to an avalanche.
Igneous, Sedimentary & metamorphic
Three types according to geologists (or some intelligentsia group).

BF
 

newmisty

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Igneous, Sedimentary & metamorphic
Three types according to geologists (or some intelligentsia group).

BF
Sedentary- tending to spend much time seated; somewhat inactive. :p
 

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Igneous
Hot to rock (and roll)

metamorphic
Stressed and compressed, kept in the crowded dark

:inspector:
BF
 

Fatrat

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Pretty rocks, thanks for the pics...
 

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BTW — y'all can download some of those photos out of my collection, iffin ya want, and use them as a desktop background slide show or as a screen saver - they look real purdy on a 60 inch display.

BF
 

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Looks like there's some rock hounds here. Maybe someone could identify these. They were part of a old watchmakers shop I bought a long time ago. When held to a bright light some are purple and some are red
 

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Hypophthalmichthys molitrix
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assuming that their all the same 'stuff'

1. will it scratch glass?
2. Can you chip a flake (like a little half-moon)?
3. I can't really tell from photos but does is it have a vitreous sheen? (Like glass)
4. does it feel slick or is it easy to grasp - what is the texture?
5. what color is the streak?

start there

BF
 

lumpOgold

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Looks like there's some rock hounds here. Maybe someone could identify these. They were part of a old watchmakers shop I bought a long time ago. When held to a bright light some are purple and some are red
That looks like Sumatran Amber, try polishing one and then if you have a UV light it might glow like this. You might also see pieces of coal stuck to the amber if it is amber.

1542209522413.png
 

Unca Walt

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There are more exceptionally clever inmates in this forum than I have ever seen anywhere else. Any subject pops up, and some PVh.D (Piled Very high Doctorate) answers brilliantly.
 

mtnman

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assuming that their all the same 'stuff'

1. will it scratch glass?
2. Can you chip a flake (like a little half-moon)?
3. I can't really tell from photos but does is it have a vitreous sheen? (Like glass)
4. does it feel slick or is it easy to grasp - what is the texture?
5. what color is the streak?

start there

BF
Scratch glass, yes
Chip a flake, yes but it's hard like glass
Vitreous sheen, Yes shiny like glass
What is the texture, Slick like glass
When held to a light it's opaque and purplish red in color.
Doesn't glow under a black light
 

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Hypophthalmichthys molitrix
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You have a streak plate? The same one you use to test gold with acid?
I am expecting a white streak
Then I would say it is probably obsidian
Red obsidian is probably kinda rare

I'll do a little research & get back to ya

BF
 

mtnman

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You have a streak plate? The same one you use to test gold with acid?
I am expecting a white streak
Then I would say it is probably obsidian
Red obsidian is probably kinda rare

I'll do a little research & get back to ya

BF
I tried it on my gold test streak plate, it scratched it!
 

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Unh, is yer plate made of ceramic, unglazed porcelain? (sorry about the scratch)
I've never had anything scratch my streak plate (but then, again, I've never had a diamond to test that)

The specific gravity of obsidian is 2.4 but it is a bitch to calculate SG of a sample.

BF
 

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If it does scratch your unglazed porcelain streak plate you might just have a box full of corundum (AKA Ruby)
Send me a chunk

BF
 

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Let's see here, density of obsidian is 2.35 g/cm³ and corundum is 4.02 g/cm³ so corundum should feel kinda 'too heavy' when you bounce it on your palm.
 

GOLDBRIX

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Looks like there's some rock hounds here. Maybe someone could identify these. They were part of a old watchmakers shop I bought a long time ago. When held to a bright light some are purple and some are red
mtnman, You are in or close to a region ( usually North Carolina) where corundum and gold can be found. If the old watchmaker's shop was in your vicinity I would say you have some sapphire corundum. Of course the closer to red it is then it's ruby.
Any red color would be a ruby. Any other colors would be called a sapphire.
The only difference is the mineral content in with the corundum.

FYI - Watch your papers and ads for any local Gem shows coming to your area: Johnson City, Bristol, Kingsport. Definitely Knoxville, Maybe the artsy folks down in Gatlinburg. It just depends on where you are at and willing to travel in your neck of the woods

Good Luck and Best Wishes,
 

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Here's a link to a good resource if ya want to tinker around trying to identify it: MinDat — lots of technical information on minerals.

BF
 

mtnman

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Unh, is yer plate made of ceramic, unglazed porcelain? (sorry about the scratch)
I've never had anything scratch my streak plate (but then, again, I've never had a diamond to test that)

The specific gravity of obsidian is 2.4 but it is a bitch to calculate SG of a sample.

BF
I guess that's what it's made of. It's a store bought product. Here's the picture. The scratch on the right is from the rock laying on the plate. I tried to polish the rock with a green scotchbrite grinding wheel, it wouldn't do anything. That same wheel polishes chips from glass. Gold has been found in my county(panning the Powell River) and the Indians have a story about gold in the Cumberland Mountain. Lots of minerals here. A very long time ago there was a lead mine here and I know where there's a Civil War era saltpeter mine. PM me with a address an I'll send you a piece. P1090516.JPG
 

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Got the piece mtnman sent me, weighs 2.96 grams. I calculated specific gravity at 4.17, which put it in the same range as corundum, but a 3 gram ruby would be a large ruby so I discarded the ruby idea. It is harder than quartz and is very translucent — a nice specimen. The guy at my LCS has a thermal conductivity meter that is used for detecting gemstone identity and the meter measured it as garnet. Since garnet fits all the other data I have gathered I would have to say that is what it most likely is.

Previously I thought garnet only showed up as those dark little round 'bucky ball' crystals embedded in matrix (I have a sample in my collection). But on researching garnet I discover that garnet comes in almost every color (Rock Auction - garnet) and the crystal structure is not always evident. Of the three basic divisions of garnet I think it falls in the grossular garnet section. Now, if the crystals were green you'd have a small fortune on your hands mtnman, but red is the most common color and, looking at the rock auction site, it appears to sell for 2 to 5 bucks a gram.

One more test I'll try to get somewhere is the refractive index (about 1.8 for garnet), if it falls in that range it I will have to say it's garnet. I'm also going to show it to one of my rock shop guys later this month and see if he concurs.

BF