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-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)
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)

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
111805


The time now is Mar 28, 2024 23:49

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.
Hunan China Calcite with Marcasite
  
  Index -> Minerals and Mineralogy
Like
6


View previous topic :: View next topic  
Author Message

John Hodgson




Joined: 14 May 2020
Posts: 16
Location: Michigan

View user's profile

Send private message

PostPosted: Dec 15, 2020 19:03    Post subject: Hunan China Calcite with Marcasite  

I am hoping that someone may have information on how this specimen formed or what it was formed on. The only thing I know about the location is that it is from Hunan China. The layer of marcasite covers the entire bottom of the specimen and is very uniform in thickness. It also is not flat and in one spot is about 2" deep. Thank you.


IMG_3165.JPG
 Mineral: Calcite & Marcasite
 Locality:
Hunan Province, China
 Dimensions: 35 cm x 23 cm x 18 cm high
 Description:
 Viewed:  5915 Time(s)

IMG_3165.JPG



IMG_3164.JPG
 Mineral: Calcite & Marcasite
 Locality:
Hunan Province, China
 Dimensions: 35 cm x 23 cm x 18 cm high
 Description:
 Viewed:  5915 Time(s)

IMG_3164.JPG



IMG_3165.JPG
 Mineral: Calcite & Marcasite
 Locality:
Hunan Province, China
 Dimensions: 35 cm x 23 cm x 18 cm high
 Description:
 Viewed:  5919 Time(s)

IMG_3165.JPG


Back to top
Reply to topic Reply with quote
Like
4
   

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: Dec 15, 2020 23:25    Post subject: Re: Hunan China Calcite with Marcasite  

You asked how this formed. One way to get this specimen is as follows. Consider a situation where there is a hole or void space (we call this a vug) deep in the ground. This hole could have opened because of ground movement or dissolution of whatever was there before. This hole is filled with fluid which originally precipitated marcasite (that is why the marcasite is there) but then stopped. Then, for whatever reason, the fluid chemistry in the hole changed so that it became supersaturated with respect to calcite. We see nice calcite crystals because they were able to grow into the hole unimpeded. Then, before the calcite completely filled the hole, calcite precipitation stopped, and we are left with what you have today.
Back to top
Reply to topic Reply with quote
Like
1
   

Tobi
Site Admin



Joined: 07 Apr 2009
Posts: 4092
Location: Germany


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Dec 16, 2020 02:51    Post subject: Re: Hunan China Calcite with Marcasite  

And by the way, this is a really really good specimen!
Back to top
Reply to topic Reply with quote
Like
1
   

John Hodgson




Joined: 14 May 2020
Posts: 16
Location: Michigan

View user's profile

Send private message

PostPosted: Dec 16, 2020 16:27    Post subject: Re: Hunan China Calcite with Marcasite  

Thanks for the reply. The marcasite has a crystalline surface. Does this mean the marcasite formed with a void on both sides and then the calcite formed on top of the marcasite? Thank you.
Back to top
Reply to topic Reply with quote
Like
   

James Catmur
Site Admin



Joined: 14 Sep 2006
Posts: 1340
Location: Cambridge


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Dec 17, 2020 04:36    Post subject: Re: Hunan China Calcite with Marcasite  

The Marcasite may have formed on another mineral that has since been dissolved. So the face you see may be a cast of the mineral that is no longer there. Look very closely at at the faces and see if they are typical of Marcasite or of another mineral.
Back to top
Reply to topic Reply with quote
Like
   

Bob Morgan




Joined: 18 Jan 2018
Posts: 226
Location: Savannah, Georgia


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Dec 17, 2020 20:35    Post subject: Re: Hunan China Calcite with Marcasite  

James' hypothesis is entirely possible, and the small marcasite crystals would not be altered to other shapes at contact. Particularly if the other mineral were calcite the interaction at contact surfaces might develop dissolution channels that enable normal crystal shapes of the small marcasites. This happens with carrollite contact surfaces with calcite.

Another thought: I've collected a calcite with crystals on the bottom from being developed in a pool and layered stalagmitic structure on top from drip action. Could something like that be involved even if with different minerals?

I'm no chemist so couldn't come up with deposit conditions in solution that might contribute to something like this. The two minerals are composed of entirely different atoms.
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 2006-2024


Powered by FMF