[Rockhounds] The Color of Rare Earth Minerals

[Andrew Turner]

Although the REE elements might be colorful when extracted and separated, most of the ore minerals that I've seen that contain them are rather ugly...black, dark brown, rootbeer brown, and brown/red.  They are often "trash can" minerals that incorporate a lot of different elements in their structure.  The shonkinite (look that up!) rock that contains the mainly bastnasite ore at Mountain Pass is often fairly dull, and the basnesite is rather small and brown.  REE minerals themselves can be rather colorful, but they are rather small and rare and aren't the ones that are mined in the major REE mines.  Thanks.

Andrew Turner
Salt Lake City, UT

________________________________
From: Rockhounds <rockhounds-bounces at rockhounds.drizzle.com> on behalf of gary brown <gbrown at catspaw-minerals.com>
Sent: Wednesday, June 12, 2019 3:55 PM
To: 'Rockhounds at drizzle.com: A mailing list for rock and gem collectors'
Subject: Re: [Rockhounds] The Color of Rare Earth Minerals

Funny man.

Thanks!

GcB

-----Original Message-----
From: Rockhounds <rockhounds-bounces at rockhounds.drizzle.com> On Behalf Of
Axel Emmermann
Sent: Wednesday, June 12, 2019 5:09 PM
To: 'Rockhounds at drizzle.com: A mailing list for rock and gem collectors'
<rockhounds at rockhounds.drizzle.com>
Subject: Re: [Rockhounds] The Color of Rare Earth Minerals

Samarium causes light green color in 3+ state in aragonite and fluorite. In
fluorite it can change to violet-grey due to sunshine and reduction to 2+
state.
Most color in minerals is caused by d-orbitals in transition metals like
iron, nickel, cobalt, copper, etc...
In REE, the d-orbitals are shielded by 5f orbitals. But there is STRONG
fluorescence in MANY minerals that contain REE. They cover the complete
spectrum with their emissions including NIR and deep UV.

Say hi to Sushi (whoever that is)
Axel

-----Oorspronkelijk bericht-----
Van: Rockhounds <rockhounds-bounces at rockhounds.drizzle.com> Namens gary
brown
Verzonden: woensdag 12 juni 2019 21:16
Aan: 'Rockhounds at drizzle.com: A mailing list for rock and gem collectors'
<rockhounds at rockhounds.drizzle.com>
Onderwerp: [Rockhounds] The Color of Rare Earth Minerals

My son (originally a chemist...now a computer geek) asked me an interesting
question over lunch (which he paid for!  Yay!):

Are "rare-earth" minerals colorful as a rule, or are they more
blue-grey-black?

"Hmmm", I said (munching down another hunk of sushi),  "I'll ask the Hive
Mind..."

And so... here I am!

Gary Brown



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