Mindat Logo
bannerbannerbannerbanner
Welcome!

Advanced

Unknown Amphibole - pyroxene

Posted by Tom Mortimer  
Unknown Amphibole - pyroxene
November 08, 2009 10:22PM
My unknown amphibole or pyroxene is from the Franconia Iron Mine, Sugar Hill, New Hampshire. It is fibrous, pale-green. Minerals on the same specimen include andradite garnet (EDS confirmed), quartz, and magnetite. A qualitative EDS analysis of this fibrous pale-green mineral indicated the presence of Si, Mg, Ca, O, Fe, and minor Al, (EDS plot below ).
The field of view for photo below is about 1 cm. Unknown mineral with red andradite garnet.
The field of view forsecond photo below is about 2 mm .
The EDS analyst suggested "a sub-calcic AUGITE pattern." None of the augite photos on mindat looks anything like this mineral. This material matches no previously reported species from this locality.
Looking for suggestions as to what this might be.

Tom Mortimer
avatar Re: Unknown Amphibole - pyroxene
November 08, 2009 11:28PM
ca    
Diopside
avatar Re: Unknown Amphibole - pyroxene
November 09, 2009 12:28AM
us    
Hi Tom,

I like Rob's idea of Diopside. One might consider somewhere in the Diopside-Hedenbergite Series to account for the Fe but sure, closer to Diopside. The other Clinopyroxene that should be considered is Augite, since it does explain the others you have like Na that are common impurities in Augite. Rightly stated I think by your analyst when suggesting "sub-calcic", Ca does seem a bit low. BTW, I'm with you, it doesn't "look" like Augite, in fact to me it actually looks visually a bit like Actinolite (an Amphibole), which does have a similar looking spectra. Just my two cents, all the best.

Ron



Edited 1 time(s). Last edit at 11/09/2009 12:35AM by Ronald John Gyllenhammer.
avatar Re: Unknown Amphibole - pyroxene
November 09, 2009 12:32AM
ru    
Typical Actinolite. As we joking "Actinolite-(Ac)"... thumbs up smiley Brother of Neptunite-(Np) and chlorite-(Cl) smiling smiley
Re: Unknown Amphibole - pyroxene
November 09, 2009 09:46AM
I would also suggest Actinolite as I have similar specimens from Arendal and Kragero, Norway.

Spencer.
avatar Re: Unknown Amphibole - pyroxene
November 09, 2009 08:33PM
ca    
O.K. I'll back off on the diopside. See if you can see any cleavage or believe the others, or x-ray it.
Re: Unknown Amphibole - pyroxene
November 10, 2009 09:01PM
Rob, Ron, Spencer, & Pavel,
Thank you for your input. I think the Actinolite identification is the best fit. I looked closely at several specimens of this mineral with up to 60x magnification. The fibers are so fine that I was unable to distinguish any cleavage. Although more common elsewhere, actinolite is a rare species for New Hampshire. Several bladed structure amphiboles from other NH localities that I thought to be actinolite have been analyzed to be ferrohornblende.

Tom Mortimer



Edited 1 time(s). Last edit at 11/11/2009 01:27AM by Tom Mortimer.
Re: Unknown Amphibole - pyroxene
November 10, 2009 10:38PM
Perhaps Tremolite.
avatar Re: Unknown Amphibole - pyroxene
November 11, 2009 06:22PM
de    
Hello,

Actinolite most likely.

Not tremolite, as there is a Ca peak.

Regards,
Sebastian Möller
avatar Re: Unknown Amphibole - pyroxene
November 11, 2009 06:39PM
us    
Hi Sebastian,

Actinolite and Tremolite both have Ca peaks, did you mean to say, "...there is an Fe peak" ? [www.cannonmicroprobe.com]

Ron
avatar Re: Unknown Amphibole - pyroxene
November 12, 2009 09:29PM
de    
Hi Jon,

Sorry, yes, I meant a Fe peak. So this is either a Fe-rich tremolite (no pure endmember) or an actinolite.

Regards,
Sebastian Möller
Author:

Your Email:


Subject:


Attachments:
  • Valid attachments: jpg, gif, png, pdf
  • No file can be larger than 1000 KB
  • 3 more file(s) can be attached to this message

Message:

Mineral and/or Locality
Google
 
www.mindat.org Web
Copyright © Jolyon Ralph and Ida Chau 1993-2009. Site Map. Locality, mineral & photograph data are the copyright of the individuals who submitted them.Further information contact the Site hosted & developed by Jolyon Ralph. Mindat.org is an online information resource dedicated to providing free mineralogical information to all. Mindat relies on the contributions of hundreds of members and supporters. If you would like to add information to improve the quality of our database, then click here to register. Current server date and time: 25th Nov 2009 08:22:17