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


Spanish message board






Newest topics and users posts
28 Mar-09:37:50 Re: 2 unknowns co-occurring with caledonite, grand reef mine, az (Cfrench58)
27 Mar-19:47:08 Re: 2 unknowns co-occurring with caledonite, grand reef mine, az (Pete Richards)
27 Mar-16:15:44 Re: 2 unknowns co-occurring with caledonite, grand reef mine, az (Cfrench58)
27 Mar-15:18:59 Re: 2 unknowns co-occurring with caledonite, grand reef mine, az (Alfredo)
27 Mar-14:39:29 2 unknowns co-occurring with caledonite, grand reef mine, az (Cfrench58)
27 Mar-05:21:48 Re: the mim museum in beirut, lebanon (Mim Museum)
27 Mar-05:03:26 Re: trying to find information on rose/pink quartz and tourmaline associations. (Ning)
27 Mar-02:39:50 Re: the mim museum in beirut, lebanon (Tobi)
27 Mar-00:23:28 Re: collection of volkmar stingl (Volkmar Stingl)
26 Mar-00:53:41 Re: collection of volkmar stingl (Volkmar Stingl)
25 Mar-13:32:10 Re: collection of michael shaw (Michael Shaw)
25 Mar-00:25:58 The mizunaka collection - quartz (Am Mizunaka)
23 Mar-13:35:22 Re: collection of firmo espinar (Firmo Espinar)
22 Mar-08:32:28 Re: collection of michael shaw (Michael Shaw)
22 Mar-04:20:41 Re: the mim museum in beirut, lebanon (Mim Museum)
21 Mar-22:49:19 Re: green seam. Looks like it in a state of decay. (Ning)
21 Mar-22:47:40 Re: green seam. Looks like it in a state of decay. (Ning)
21 Mar-22:45:25 Re: green seam. Looks like it in a state of decay. (Ning)
21 Mar-15:34:23 Re: the mizunaka collection - quartz (Am Mizunaka)
21 Mar-14:35:08 Re: jim’s mineral collection (Jim Wilkinson)
21 Mar-14:15:36 The 4th phoenix heritage mineral show (phms) hosted by mineralogical society of arizona (m (Chris Whitney-smith)
21 Mar-04:36:10 Re: the mizunaka collection (Tobi)
21 Mar-04:11:47 Re: jim’s mineral collection (James Catmur)
20 Mar-23:34:15 The mizunaka collection - quartz (Am Mizunaka)
20 Mar-18:13:16 Re: jim’s mineral collection (Jim Wilkinson)

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
111802


The time now is Mar 28, 2024 13:40

Search for a textSearch for a text   

A general guide for using the Forum with some rules and tips
The information provided within this Forum about localities is only given to allow reference to them. Any visit to any of the localities requires you to obtain full permission and relevant information prior to your visit. FMF is strictly against any illicit activities related to collecting minerals.
Bismuth lost its colours.
  
  Index -> Conserving, Preparing and Cleaning Minerals
Like
1


View previous topic :: View next topic  
Author Message

cornz




Joined: 05 Nov 2018
Posts: 6
Location: Cheshire

View user's profile

Send private message

PostPosted: Nov 05, 2018 14:27    Post subject: Bismuth lost its colours.  

Hi all.
I have a lovely piece of bismuth but all its colours have disappeared.
I thought it might have oxidised so tried some polish, no different so i decided to up the ante and clean it in a mild solution of citric acid.
Its come up lovely, a beautiful silver colour but thats it. The coloured banding has vanished completely.
Short of remelting it, i assume there is no way to recover the colours?
Thanks.
Cornz.
Back to top
Reply to topic Reply with quote
Like
   

alfredo
Site Admin



Joined: 30 Jan 2008
Posts: 979


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Nov 05, 2018 14:59    Post subject: Re: Bismuth lost its colours.  

The short answer is no, you can't, or at least not easily. Those colors are an optical thin film effect, produced by an extremely thin oxide layer on the surface, just a few molecules thick, and you've now cleaned that layer off. So what you're seeing now is the TRUE color of bismuth, silver with a very slight pinkish tint, which I find preferable to the fake rainbow colours.
if you really want to reestablish the colourful oxide layer, you could try giving it a bath in some oxidizing liquid, but lots of experimentation will be needed to get the right thickness, because a tiny change in the thickness of that surface film is going to make a big difference to the colours you see, or whether you even get any colours at all.
Back to top
Reply to topic Reply with quote
Like
1
   

Recovering - Academic




Joined: 24 Apr 2018
Posts: 316

View user's profile

Send private message

PostPosted: Nov 05, 2018 15:04    Post subject: Re: Bismuth lost its colours.  

cornz wrote:
Hi all.
I have a lovely piece of bismuth but all its colours have disappeared.
I thought it might have oxidised so tried some polish, no different so i decided to up the ante and clean it in a mild solution of citric acid.
Its come up lovely, a beautiful silver colour but thats it. The coloured banding has vanished completely.
Short of remelting it, i assume there is no way to recover the colours?
Thanks.
Cornz.


Hello:

Bismuth melts at 271 degrees C. Try heating it to about 150 degrees C (electric cooking oven) and keep the Bismuth at this temperature to see if the colors return. If not try increasing the temperature but avoid going too close to the melting point (<210 degrees C).

When I have cast Bismuth I have noted that the colours occur just after the melt solidifies.

_________________
“The further a society drifts from the truth, the more it will hate those that speak it.”

― George Orwell
Back to top
Reply to topic Reply with quote
Like
   

Pete Modreski
Site Admin



Joined: 30 Jul 2007
Posts: 709
Location: Denver, Colorado


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Nov 05, 2018 18:10    Post subject: Re: Bismuth lost its colours.  

I never heard of those colors on bismuth fading before, so, wonder why that happened to yours?
Back to top
Reply to topic Reply with quote
Like
   

mmauthner




Joined: 30 May 2007
Posts: 113
Location: Graz

View user's profile

Send private message

PostPosted: Nov 06, 2018 01:32    Post subject: Re: Bismuth lost its colours.  

Pete,
The same thing happens to the iridescent colours of the Yukon (Husky Mine) stephanites and polybasites. Actually, all of the minerals from there that have the iridescent coating...
Anyone that has such a specimen is advised to keep it in the dark if one wants to preserve those colours.
Mark
Back to top
Reply to topic Reply with quote
Like
   
Display posts from previous:   
   Index -> Conserving, Preparing and Cleaning Minerals   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 2006-2024


Powered by FMF