Question for geologists

[Cabal]

I was wondering would any of the geologists (or anyone else for that matter) be able to help me - the local healing crystal store in my town (pseudoscience aside, the only place for miles where I can augment my mineral collection, pretty good selection too) is selling a stone claimed as the "oldest existing mineral (3bn years old)" - the only name it goes by is "nummit." Here's a picture of the only slice they have:

It's quite heavy for its size (not that much bigger than this picture), and it has glimmering gold-brown streaks in it. I can't find anything out about it online at all.

My interest is piqued, but given that this shop, while generally fairly capable in terms of selling genuine articles, occasionally does lapse into some really wacky stuff, I'm tempted to call shenanigans on this one.

Any of you guys heard of it? Does it go by another name? "Nummit" doesn't exactly sound too technical.

 

[Baggins]

Nummit means nothing to me.

Its heft and the gold brown colour make me think of Iron pyrites, but I'd have to look and even thenit would be a bit dodgy.

The dating must be bogus unless they can tell you which rock formation it came from.

Do you own an xray diffraction machine?

 

[Baggins]

http://www.psychesgarden.co.uk/Crystals/N/Nummit.html

ning nang nong

Seems to be a name specific to crystal healers with a dodgy grasp of mineralogy and the dating of the earth to me:

"Nummit - Astrological signs of Sagittarius. Excellent for chakra work and removing energetic blockages, repair the auric fields, helps to allow a person to release from there own imposed limits."

"The oldest living mineral, was formed over 3 billion years ago."

Living mineral?

 

[thaumaturgy]

That's a new one on me!

Back in grad school I was working at a rock shop and I was, at that time, really "into" the mineral epidote. I was teaching a mineralogy lab at the time and worked the rock shop in town part-time.

One day a woman comes in and asks the magic question: "Could you tell me anything about this mineral epidote?" (We had a really nice specimen).

Oh my, I started in with the whole silicates and sorosilicates thing, I was just about splewing there on the counter, gushing over this wonderful specimen...

I was just getting into the nature of sorosilicates when she stops me and says "No, no, I want to know about the healing properties."

Talk about let-down!

Then a couple weeks later this dude comes in and asks about big piece of fluorite we had. It was a piece from my home state, our state mineral. I started talking about the wonders of fluorite mineralogy and the history of its economic usage, and he just sort of wanders off and says "No, I'm looking for a 'purple' mineral." Turns out he was an interior designer and just looking for a specific color.

Often times it doesn't pay to actually love minerals when you work in the market.



Sorry I can't help you on this Nummit thing. If Baggins' find is any indication, you might be running into the "healing" stuff and wandering afield of actual minerals.

Let us know if you find anything further out about it!

 

[Cabal]

Cheers for the help guys.

Yeah....that psyche's garden place is my local rock shop....they do have some awesome stuff though - just bought a beautiful celestite geode today. Next on my list are one of each of their huge chunks of labradorite, malachite and stibnite. My dream is to create a personal collection of fluorescent and radioactive rocks (complete with appropriate display/storage - UV fish tank and lead pigs ahoy).

The only other possible thing I've found, again unfortunately from crystal healing pages is that it may be related to kyanite. Now, whether they mean it's geologically/chemically similar or similar in that it "realigns your chakras" etc, I can't tell.

I do want to find out more about this though, I guess I'd like to give my store the benefit of the doubt, I've made acquaintances with several of the staff and while they're capable of holding forth at length on "crystal frequencies" (got a serious longing to turn on a radio in that store sometime to prove them utterly wrong) they're also quite happy to sit and discuss the rocks in physical/chemical/geological terms with a cold hard cynic like me, and they're a lot more knowledgeable about that side of things than I would have given them credit for originally.

But yes, this nummit one is a toughie.

 

[Cabal]

Got it.

And it was the name that was throwing me off. Nummit is aka Nuummite, a rare metamorphic rock from Greenland.

http://www.minershop.com/html/nuummit_mindata.html
http://www.thaigem.com/infocenter/buyer_guides/a-z_gemstones/nuummit.asp

Must be rare, that 2-inch long shard I showed you before costs 70 pounds sterling :s

 

[thaumaturgy]

My dream is to create a personal collection of fluorescent and radioactive rocks (complete with appropriate display/storage - UV fish tank and lead pigs ahoy).

I'm not overly fond of the radioactive ones myself, but fluorescent stuff is cool. If you are ever in the States you have got to hit Sterling Hill in New Jersey. It's an old FRANKLINITE mine. The associated carbonates and willemite fluoresce a variety of colors. I toured the mine (it's a museum now) back in the early 90's and it's all in a marble deposit. So the mine adits are these long "marble hallways" and at one point they cut the lights out and turn on a blacklight and you see a big strip across the wall of fluorescence from floor to ceiling, about 10 feet in lenght and about 3 feet wide. It is really neat.

Great tour overall and a neat place.

We were allowed to grab a free sample at the end of the tour. This was a thrill for me because about 5 years earlier in my mineralogy class in the middle of the U.S. our teacher talked very briefly about Franklinite and how it was an extremely rare mineral and we didn't have any to look at in class. So now it has top billing in my admittedly limited minerals collection!

The only other possible thing I've found, again unfortunately from crystal healing pages is that it may be related to kyanite.

Kyanite is neat! I like the two different hardnesses based on direction.

they're also quite happy to sit and discuss the rocks in physical/chemical/geological terms with a cold hard cynic like me, and they're a lot more knowledgeable about that side of things than I would have given them credit for originally.

Excellent! It does amaze me how sometimes I'm willing to write a "crystal head" off but in reality they sometimes do develop a real background and can hold their own. Hats off to 'em.

Best of luck with your collection, and do take care around the radioactive ones!

 

[thaumaturgy]

Got it.

And it was the name that was throwing me off. Nummit is aka Nuummite, a rare metamorphic rock from Greenland.

http://www.minershop.com/html/nuummit_mindata.html
http://www.thaigem.com/infocenter/buyer_guides/a-z_gemstones/nuummit.asp

Must be rare, that 2-inch long shard I showed you before costs 70 pounds sterling :s

NOW I'm intrigued! Greenland is on my list of places I'd like to visit (along with Antarctica and Svalbard). Do you still have to get permission from the Danish authorities to visit Greenland?

So it's a mixture of a couple of amphiboles? Very nice looking pieces in those pics. I like the irridescence.

You earlier mentioned labradorite. My wife and I on a trip to Newfoundland picked up a nice big piece of labradorite. I am quite fond of the diffraction-grating color play.

A few years later I was in Finland and picked up a couple "Spectrolite" earrings for my wife. It looked very much like labradorite, but the Finns assured me it was much, much nicer than labardorite.

When they found out my wife and I were geologists (me by degree since I'm now officially a chemist by trade), they threw in a chunk of spectrolite for free.

 

[MewtwoX]

Nummit means nothing to me.

Its heft and the gold brown colour make me think of Iron pyrites, but I'd have to look and even thenit would be a bit dodgy.

The dating must be bogus unless they can tell you which rock formation it came from.

Do you own an xray diffraction machine?

"CAN I BRING AN X-RAY DIFFRACTION MACHINE INTO YOUR STORE?"

Shopkeep: ;

 

[juvenissun]

a stone claimed as the "oldest existing mineral (3bn years old)" - the only name it goes by is "nummit." Here's a picture of the only slice they have:

It's quite heavy for its size (not that much bigger than this picture), and it has glimmering gold-brown streaks in it. I can't find anything out about it online at all.

Just go by the small image:

Not labradorite.
Not pyrite,
Not amphiboles or amphibolite.
It is not a mineral. It is a rock.
The 3 by age is definitely a hoax.

I wonder why is it presented as a thin slab. Is it possible for this piece to have somekind of foliation? (do you know how to see it on a polished piece?). If it is foliated, then the choice becomes very limited.

In addition to the golden streaks, you may pay attention to see if there is any other larger size "streaks" or "spots". If not, then it is simpler and would also be less valuable.

One thing puzzles me on your description is the weight. I am not sure why would this piece be heavier than normal. The image does not give me an impression that it is abundant in metals (it is translucent and are not uniform in transparency).

I would not buy it if it asked more than $25.

 

[Baggins]

Got it.

And it was the name that was throwing me off. Nummit is aka Nuummite, a rare metamorphic rock from Greenland.

http://www.minershop.com/html/nuummit_mindata.html
http://www.thaigem.com/infocenter/buyer_guides/a-z_gemstones/nuummit.asp

Must be rare, that 2-inch long shard I showed you before costs 70 pounds sterling :s

Sounds like a metamorphic lava then, an amphibolite.

http://en.wikipedia.org/wiki/Amphibolite

So all they did was misspell the name of the mineral and erroneously claim it is the worlds oldest mineral.

I was miles off, shows doing remote geology is a fools game as I thought this would turn out to be fools gold

 

[ChordatesLegacy]

Slightly off subject; but the word in question is found in a old local dialect of the Swansea area, Wales

Nummit a light meal sent to harvesters in the field (noon meat)

 

[juvenissun]

Got it.

And it was the name that was throwing me off. Nummit is aka Nuummite, a rare metamorphic rock from Greenland.

http://www.minershop.com/html/nuummit_mindata.html
http://www.thaigem.com/infocenter/buyer_guides/a-z_gemstones/nuummit.asp

Sorry that I did not read the links before my last reply. My guess was partially right and partially wrong. I still insist that it is not an amphibolite. I rather call it a "black jade".

It makes some sense to me now that this rock could be old. The key is that it is Mg rich and is nearly Fe free. However, this also make this rock less desirable as a gemstone. It is soft and friable. In fact, I don't see how could it be evaluated as a gem except its rarity. For this particular piece, the thinness is the biggest problem. I guess one could crack it pretty easily with hand.

I don't like the color. Otherwise, I will pay $100 for it.

Thanks.

 

[thaumaturgy]

It makes some sense to me now that this rock could be old. The key is that it is Mg rich and is nearly Fe free.

Not following here. What's the link between age and Mg/Fe abundances?

However, this also make this rock less desirable as a gemstone. It is soft and friable.

Apatite and cultured pearls are both reasonably soft. Pearls around 2.5 to 4.5. Semi-precious apatite has a hardness of 5 and this Nuumite appears to be around 5-5.5.

I don't recall that valuation as a "gem" is necessarily a function of hardness. But perhaps within the trade it matters. It certainly affects where the gem is utilized as ring vs pin etc.

In fact, I don't see how could it be evaluated as a gem except its rarity.

Why not? Rarity can certainly help make a stone more valuable.

 

[juvenissun]

Not following here. What's the link between age and Mg/Fe abundances?

Of course only high-Mg rock is not enough to indicate old age. However, if it is from Greenland, then the probability becomes very high. This rock is not datable by conventional method. The date is most likely inferred by the geological province.

Think about this question: how could this low grade metamorphic rock exist in associated with the Archaean craton of Greenland?

 

[Baggins]

Think about this question: how could this low grade metamorphic rock exist in associated with the Archaean craton of Greenland?

Ummmmm, that's a toughie, how about because it hasn't been affected by either high temperatures or pressures?

Because you are such a brilliant geologist and all I assumed you knew there were sedimentary rocks on Greenland 3.8 billion years old.

Old rocks don't have to be metamorphosed you know.

 

[Baggins]

http://www.lpi.usra.edu/education/timeline/gallery/slide_21.html

Picture of same. Enjoy.

 

[juvenissun]

Ummmmm, that's a toughie, how about because it hasn't been affected by either high temperatures or pressures?

Because you are such a brilliant geologist and all I assumed you knew there were sedimentary rocks on Greenland 3.8 billion years old.

Old rocks don't have to be metamorphosed you know.

As I can remember, this is the first time I appreciate your comment.

Yes, it is quite true. But I do not understand why. How did they escape the multiple times of orogenesis and not be affected. The only way I can see it is there was not multiple orogenesis at that particular place. But that itself demands an explanation.

Back to the OP. The only way I can see this rare rock be formed is an event of obduction which pushed a piece of oceanic dunite (not basalt nor gabbro) onto the Archean Greenland. But it was only weakly metamorphosed. So the time of metamorphism must be later than those higher grade cratonic gneisses. So, the time of emplacement could be in between Archean and early Proterozoic. We know most Proterozoic stuff on Greenland are sedimentary.

 

[Baggins]

Yes, it is quite true. But I do not understand why. How did they escape the multiple times of orogenesis and not be affected. The only way I can see it is there was not multiple orogenesis at that particular place. But that itself demands an explanation.

I don't see why the absence of any strong orogenic influence over SW Greenland needs an explanation, does everywhere on earth need to be heavily affected by an orogeny or two?

If this area has been towards the center of a shield area for billions of years I see no reason for metamorphism, there are similar very ancient sedimentary rocks in the middle of the Australian shield as well, most greenstone belts have elements of sedimentary rocks are by their nature they are not heavily metamorphosed.

 

[juvenissun]

I don't see why the absence of any strong orogenic influence over SW Greenland needs an explanation, does everywhere on earth need to be heavily affected by an orogeny or two?

That is my question. It has been a question in my mind for decades, just never got time to look at it on the front. Let's say the supercontinent cycle is once every 500-700 m.y., then there should have been several happened in the past. And in average, there is likely to be a number of regional collisions happened before one supercontinent event is completed (such as the Rocky, the Alps, in facts, all the current active mountain belts). So, it seems to me that the chance for any old sedimentary rock to escape metamorphism is slim. Let's say some sediments could be deposited in the continental interior. But erosion should take care of those lucky sediments already.

Of course, people argued that old collisions are weak and only made low to median grade metamorphism. But the size of old continents are also small. So it could be affected by a stronger later collisions. For example, the root area of the Rocky Mountain is 1000 miles behind the Pacific front, but it must have been, or is still affected by the collision initiated about 60 m.y. ago.

Also, if we see the Archaean rocks in Greenland are mostly high grade gneisses, then an apparent question would be: how could the gneiss be made by weak collisions during the Archaean time? If this rare rock is associated with the Archaean gneisses, how could it escape the higher grade metamorphism?

Just a thought, not an argument against what you said.

If this area has been towards the center of a shield area for billions of years I see no reason for metamorphism, there are similar very ancient sedimentary rocks in the middle of the Australian shield as well, most greenstone belts have elements of sedimentary rocks are by their nature they are not heavily metamorphosed.