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
29 Mar-09:43:41 Re: trying to find information on rose/pink quartz and tourmaline associations. (Josele)
29 Mar-09:31:55 Re: identification question (Bob Carnein)
29 Mar-08:09:52 Re: collection of tobi (Tobi)
29 Mar-07:25:48 Re: collection of volkmar stingl (Tobi)
29 Mar-06:20:21 Re: identification question (James Catmur)
29 Mar-00:03:53 Identification question (Jim Wilkinson)
28 Mar-23:16:36 Re: collection of volkmar stingl (Volkmar Stingl)
28 Mar-18:25:15 Re: collection of firmo espinar (Firmo Espinar)
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)

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
111817


The time now is Mar 29, 2024 09:48

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.
Is this Calcite or Dolomite
  
  Index -> What is it? - Where is it from?
Like
12


View previous topic :: View next topic  
Author Message

xdxucn




Joined: 24 May 2014
Posts: 100
Location: Shanghai


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Jul 29, 2020 23:26    Post subject: Is this Calcite or Dolomite  

I've got a piece of specimen, which said to be Galena+Calcite from Russia.

In Rock and Gem magazine, April 2017, there's an article "Is it Calcite or Dolomite". In the article, it says that it is Dolomite not Calcite. I'm confused. Any one could give me a clear answer? Thanks

Xiao-dong



06.JPG
 Mineral: Galena
 Locality:
Dalnegorsk, Dalnegorsk Urban District, Primorsky Krai, Russia
 Description:
 Viewed:  6000 Time(s)

06.JPG


Back to top
Reply to topic Reply with quote
Like
8
   

Matt_Zukowski
Site Admin



Joined: 10 Apr 2009
Posts: 707
Location: Alaska


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Jul 30, 2020 03:34    Post subject: Re: Is this Calcite or Dolomite  

Are you talking about the August 27, 2019 article, with a picture at the bottom that looks like your specimen? The caption in this article says that that specimen came from a "borate mine in far-east Siberia."
https://www.rockngem.com/is-it-calcite-or-dolomite/

The borate mines in far-east Siberia are in Dalnegorsk, and this search for dolomite in the Dalnegorsk region shows specimens that look like yours, especially from the 2nd Sovetskii Mine.
https://www.mindat.org/gallery.php?loc=2635&min=1304

BTW - that is a beautiful specimen.
Back to top
Reply to topic Reply with quote
Like
1
   

John Betts




Joined: 07 Jun 2012
Posts: 207
Location: New York City

View user's profile

Send private message

PostPosted: Jul 30, 2020 09:36    Post subject: Re: Is this Calcite or Dolomite  

A simple hardness test will distinguish between calcite and dolomite Can you scratch the crystals on your specimen with a calcite crystal? Do your crystals scratch calcite?
_________________
John Betts
Back to top
Reply to topic Reply with quote
Like
1
   

vic rzonca




Joined: 18 Nov 2008
Posts: 820
Location: MA


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Jul 31, 2020 07:10    Post subject: Re: Is this Calcite or Dolomite  

Both are carbonates. Calcite is calcium carbonate, dolomite is calcium magnesium carbonate. I'm not sure I've answered the question you've asked.
Back to top
Reply to topic Reply with quote
Like
   

Jesse Fisher




Joined: 18 Mar 2009
Posts: 628
Location: San Francisco


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Jul 31, 2020 10:46    Post subject: Re: Is this Calcite or Dolomite  

As Vic mentioned, calcite is calcium carbonate, and dolomite is calcium, magnesium carbonate. Some sort of chemical test for magnesium would distinguish them, but would cost a bit. Physically, calcite is softer than dolomite. Calcite has a hardness of 2.5 - 3, where-as dolomite is 3.5 - 4. Dolomite will scratch calcite, but not the reverse. Also, dolomite is less soluble in cold acids (such as HCl) than calcite. If a bit of it fizzes readily in acid, it is likely calcite, if slowly then dolomite is likely.
Back to top
Reply to topic Reply with quote
Like
   

Bob Harman




Joined: 06 Nov 2015
Posts: 765


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Jul 31, 2020 11:40    Post subject: Re: Is this Calcite or Dolomite  

I find the responses to this poster's question.....showing off his specimen.....interesting.

The only really spot on statement was Matt Z's comment: "BTW, that is a beautiful specimen".

John B's suggestion to 'scratch the crystals' to help identify the mineral seems to me to be dangerous. There is a high likelyhood that attempting that, might just knock a crystal off, and even just scratching one damages "the beautiful specimen". For this particular specimen, do not(!) attempt what John B suggests.

What Jesse F suggests might be true, but for this particular small size "beautiful specimen" finding a safe area to put acid on the crystals for testing is just as unappealing to me.
[There is just no area that allows acid testing without being visible.]

For this particular hi quality specimen with small and rather delicate calcite/dolomite crystals delicately attached to the galena, do not attempt anything that just might ruin or damage your example.

To resolve the basic mineral identification question, I would review other similar examples from this locality; some should have the mineral ID known. My opinion, Bob
Back to top
Reply to topic Reply with quote
Like
2
   

John Betts




Joined: 07 Jun 2012
Posts: 207
Location: New York City

View user's profile

Send private message

PostPosted: Jul 31, 2020 20:52    Post subject: Re: Is this Calcite or Dolomite  

Just determine the hardness. It is not rocket science. If you are willing to perform basic tests, then why post to this forum.
_________________
John Betts
Back to top
Reply to topic Reply with quote
Like
   

xdxucn




Joined: 24 May 2014
Posts: 100
Location: Shanghai


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Jul 31, 2020 22:42    Post subject: Re: Is this Calcite or Dolomite  

Thanks for the answer. Maybe I can do a little hardness test on the back corner side of the specimen. And I will let you know the result.

As for identification of similar samples, some says it's calcite, some says it's ferroan calcite, in the Rock&Gem magazine, it says it's dolomite, and the label coming with the specimen says it's calcite. Maybe I should identify it myself sometime later. :)
Back to top
Reply to topic Reply with quote
Like
   

Matt_Zukowski
Site Admin



Joined: 10 Apr 2009
Posts: 707
Location: Alaska


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Aug 01, 2020 01:52    Post subject: Re: Is this Calcite or Dolomite  

The fizz test is also useful, and can be done on a very small area of the sample, so don't forget about that.

Another thing to look for are saddle-shaped xtals or aggregates of xtals. Dolomite sometimes shows pronounced curved xtal faces. I don't see any curved xtal faces in the picture, and that doesn't rule out dolomite, but maybe there are some curved faces you can see, which would suggest it is.

Frankly, based on the pictures in the R&G article and those from mindat, I'd feel comfortable calling it dolomite. But i also wouldn't be above doing hardness and fizz testing.
Back to top
Reply to topic Reply with quote
Like
   
Display posts from previous:   
   Index -> What is it? - Where is it from?   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