We use cookies to show content based on your preferences. If you continue to browse you accept their use and installation. More information. >

FMF - Friends of Minerals Forum, discussion and message board
The place to share your mineralogical experiences

FMF English Forum is moderated by John S. White and Peter Megaw
 

Spanish message board






Newest topics and users posts
21 Apr-07:18:32 Re: galena, kommern (Montanpark)
21 Apr-06:59:50 Re: death of heimo hellwig (Peter Lemkin)
21 Apr-06:00:04 Re: galena, kommern (Matt_zukowski)
21 Apr-05:35:57 Re: death of heimo hellwig (Joan Martinez Bruguera)
21 Apr-04:16:36 Re: galena, kommern (Mathias)
21 Apr-03:16:24 Re: galena, kommern (Mathias)
21 Apr-01:38:57 Re: more from the closed lapidary (Steveb)
21 Apr-01:05:33 Re: galena, kommern (Gerhard Brandstetter)
21 Apr-00:59:06 Re: anyone has a tumbler? (Peter Lemkin)
21 Apr-00:31:08 Re: galena, kommern (Tobi)
20 Apr-23:27:50 Re: anyone has a tumbler? (Bontix77)
20 Apr-23:24:41 Re: death of heimo hellwig (Heimo Hellwig)
20 Apr-22:08:57 Re: galena, kommern (Deborah Deitsch-perez)
20 Apr-20:38:28 Re: galena, kommern (Joseph Doliveira)
20 Apr-19:50:08 Re: more from the closed lapidary (Rweaver)
20 Apr-19:40:32 Re: anyone has a tumbler? (Steveb)
20 Apr-19:25:03 Re: galena, kommern (Kevin Conroy)
20 Apr-19:21:29 Re: more from the closed lapidary (Bob Harman)
20 Apr-19:06:48 Re: galena, kommern (Richard Arseneau)
20 Apr-17:50:51 Anyone has a tumbler? (Bontix77)
20 Apr-17:31:03 More from the closed lapidary (Jadeybird)
20 Apr-16:34:08 Re: galena, kommern (Montanpark)
20 Apr-16:30:27 Re: galena, kommern (Montanpark)
20 Apr-15:03:10 Re: galena, kommern (John Betts)
20 Apr-15:00:59 Re: galena, kommern (Mathias)

For lists of newest topics and postings click here


RSS RSS

View unanswered posts

Why and how to register

Index Index
 FAQFAQ RegisterRegister  Log inLog in
 {Forgotten your password?}Forgotten your password?  

Like
54093


The time now is Apr 21, 2019 07:24

Search for a textSearch for a text   

A general guide for using the Forum with some rules and tips
common opal cluster
  
  Index -> Minerals and Mineralogy
Like
2


View previous topic :: View next topic  
Author Message

Catahoula




Joined: 13 Mar 2019
Posts: 17
Location: California, USA

View user's profile

Send private message

PostPosted: Mar 21, 2019 20:57    Post subject: common opal cluster  

Hello All, A great day today. I pulled three interesting pieces out of the ground and I need a little help.

First is this common opal cluster (Tony Kampf took a stab at identifying from an image noting it was likely common opal in a hematite breccia). The longest spear is over 8" in length and it is clustered together with others. The first image is for proportion and to understand what a cross-section of the opal looks like. It is a wonderful orange-sherbet swirl. I have pulled about 40 similar pieces out, but this one was special.

Question 1 is "how do I clean this? I have soaked in soapy water for a few days. Tried both vinegar and muriatic acid with no dent at all. I can use a dremel to etch out some of the clay soil, but I am afraid to etch into the opal.

Second question is, is this specimen any good? Is it worth saving, cleaning and displaying? The whole concept of "common opal" is an oxymoron to a neophyte like me.

Several images to follow. Thank you for your sage advice.

Jess



IMG_1276.jpg
 Mineral: Common Opal in Hematite Breccia (?)
 Description:
Southern Sierra Nevada Mtns
20cm x 5cm
The slices show what the common opal spears look like inside.
 Viewed:  332 Time(s)

IMG_1276.jpg


Back to top
Reply to topic Reply with quote
Like
1
   

Catahoula




Joined: 13 Mar 2019
Posts: 17
Location: California, USA

View user's profile

Send private message

PostPosted: Mar 21, 2019 21:06    Post subject: Re: common opal cluster  

second image of cluster


IMG_1281.jpg
 Mineral: common opal with hematite breccia
 Description:
 Viewed:  323 Time(s)

IMG_1281.jpg


Back to top
Reply to topic Reply with quote
Like
   

Catahoula




Joined: 13 Mar 2019
Posts: 17
Location: California, USA

View user's profile

Send private message

PostPosted: Mar 21, 2019 21:08    Post subject: Re: common opal cluster  

third image of cluster


IMG_1301.jpg
 Mineral: common opal in hematite breccia
 Locality:
California, USA
 Description:
 Viewed:  322 Time(s)

IMG_1301.jpg


Back to top
Reply to topic Reply with quote
Like
   

Peter Megaw
Site Admin



Joined: 13 Jan 2007
Posts: 839
Location: Tucson, Arizona


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Mar 21, 2019 21:17    Post subject: Re: common opal cluster  

Common opal refers to the fact it has no fire or play of color, which would make it Precious Opal. These are colloquial terms...there are a number of types of opal distinguished by whether they are amorphous or crystalline at the microscopic level. There are a mumver of scholarly papers on opal varieties...you might start with some by Eloise Gaillou or Emmanuele Fritsch, experts in the field.

Opal value stems from color or play of color, so if your material does not show these its value will be personal to you and removing the iron oxide staining would become a personal decision.

It looks like the iron oxide may be included in the opal...ie an integral part you can't remove. However, some may come off with care or by using a cleaning product called Iron Out you can get at Ace Hardware or online at eBay. IO works fastest in hot water but not too hot as you don't want to craze the opal. As always, first try a piece you don't care about to see if it helps or hurts...

_________________
Siempre Adelante!
Back to top
Reply to topic Reply with quote
Like
   

Catahoula




Joined: 13 Mar 2019
Posts: 17
Location: California, USA

View user's profile

Send private message

PostPosted: Mar 21, 2019 21:22    Post subject: Re: common opal cluster  

Thank you. I will let you know how it turns out.
Back to top
Reply to topic Reply with quote
Like
   
Display posts from previous:   
   Index -> Minerals and Mineralogy   All times are GMT - 5 Hours
Page 1 of 1
    

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum


All pictures, text, design © Forum FMF 2006-2019


Powered by FMF