5 August 2011
Purple everywhere! Samples from the Harding Pegmatite
Posted by Jessica Ball
All right, I’m finally getting to this post (cross-country driving trips aren’t good for keeping up with posting, apparently). My last post about the Harding Pegmatite Mine near Dixon, New Mexico had some lovely photos of the mine, but not so many of the rocks and minerals close-up. The samples I have are a little far from home (seeing as I’ve dragged them to the East coast from New Mexico), but they’re still as impressive as they were at the mine!
First, my favorite sample: one with beryl, potassium feldspar, and apatite all in one.
This is the first time I’ve seen beryl (beryllium aluminum silicate) in-situ, and it was hard to pick out at the mine, because there’s so much milky quartz lying around. The beryl here is massive rather than forming distinct crystals, and the best way to tell it apart from the quartz is by the lustre (how light reflects off the mineral): this beryl has more of a waxy or greasy lustre, while the quartz tends to be more vitreous (glassy). The apatite is a beautiful dark blue-gray here; no nice crystals, but a pretty striking color.
One of the most striking things about the mine was the abundance of colorful micas – namely purple lepidolite and the more pinkish “rose muscovite”. It was sometimes hard for me to tell the difference between the two – I think they’re both lithium-rich, although the rose muscovite seems to have smaller crystals and form crusts here, while the lepidolite appears to come in larger mica “books”.
There’s more than just pegmatite at the mine, however – the country rock is pretty neat too. It’s metamorphic, with (I believe) mica schist below the pegmatite and amphibolite above. Both rock types are abundant in the tailings, but I mainly picked up amphibolite. Here’s a neat sample with little bits of biotite mica:
Naturally, when I mentioned that mica shows up in cosmetics, it precipitated a round of sparkly vampire jokes.
This sample looked a little more schist-y to me, but came from an amphibolite-rich tailings pile.
Finally, if you hike around the back of the mine works, you can find a lovely little pit full of calcite. Some of it is close to “optical grade”, which means it’s clear enough to use in optical instruments. It’s hard to find the clear kind, though (according to the caretaker it was depleted by the younger mine visitors, who find it more appealing than the other minerals).
There were (of course) lots of other minerals there, but I had to be selective when packing my rock samples (gas mileage is important when you’re driving 2000 miles in a trip). Since it was the first time I’d seen many of these outside of a museum or mineralogy lab, I’m glad I got to pick up samples of these!
During the years that I lived in El Paso, the Harding Mine was one of those places that I often heard about, but never got to visit. I am glad you got to experience it.
I love these photos, I ought to visit the Harding Mine one day.
Beautifulo pics – thanks for sharing. I have some samples of lepidolite from a pegmatite in the Keystone area of the Black Hills of South Dakota along with beryl and tourmaline collected back in the 80’s. Lovely stuff!!
I am so pleased you posted these Harding specimens. My partner and I had a thrilling and blissfully silent day at Harding last summer, and we picked up just about the same specimens you photographed. The blue apatite is a beauty. I got a lot of lepidolite and muscovite, too and some chunky beryl from the tailings
If you know of any tourmaline-hounding in Maine trips this summer, I am interested. Thanks, Michael
I’m not very familiar with Maine’s mining, but a quick search turned up a lot of information about the Mount Mica mine, which appears to be famous for tourmaline. You might start there! http://digmainegems.com/
Jessica: Did I say thanks? I was at the Am Mu of Nat Hist Hall of Gems today and found splendid specimens from my own NY State.
Great! And I’m glad I could give you a place to start. (I’ll bet you saw some Herkimer “diamonds”…)
Thanks for the photos and info, Jessica. I’m a long time New Mexcian but just heard about the Harding mine this week. Could you send me the contact info so I could plan a visit there? Need directions too. Thanks so much!
I can get you this info. We were there last summer and it was great. Just give me a couple of days.
You’ll love it. Be sure to go on a Sunday — no bulldozers. (There is excavation going on — at least there was last August).
New York City
Kathleen: Here is the link that will give you everything you need. Be sure to contact Gilbert Griego and have him meet you at the mine — go on a Sunday.
Good luck, Michael in New York
The Museum of Natural History hads a whole showcase about the Paterson, NJ minerals from the basalt quarry that yielded prehnite. The quarry has been condo-ed over. Where else to rockhound for prehnite?
Native New Yorker
We have lived very near the Harding mine for years. I have gathered some very amazing specimens and cut grade stuff the most unique being blue appetite full shaft on a white beryl / lepidolite, but its very rare to find intact blue appetite, (mostly chips), I would say we’re quite addicted to the place! By the way The Harding Mine is very exclusive to what we call grape jelly lepidolite AMAZING PURPLE COLOR. I’m a collector and a cutter & my friends & I say go if ya can cause its beautiful, serine, & ya might not be allowed one day in the future…
The rose muscovite is redder. You have it in one picture above. Also, the whitish beryl has a bit of a pink hue to it. I’m not sure if the mine is still open to collecting??
Forty years ago, a permit from the New Mexico Bureau of Mines (Socorro) was required. We visited with our young kids. Then the adit entries were accessible, and we wore hard hats of course. The outside quarry was great too. We also went upslope to the calcite and Iceland spar excavation. I still have some calcite and lepidolite chips that I haven’t given away to neighbor kids.
The spodumene inclusions (6-6.5 hardness) make sawing and grinding for mounting purposes difficult, as I gave up my old lubricated diamond saw decades ago. I’ve recently mounted one to give to my granddaughter.