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
18 Mar-08:12:52 Green seam. Looks like it in a state of decay. (Ning)
18 Mar-06:47:13 Mineralogy & museums 10 - cardiff - 12th-13th august 2024 (Roy Starkey)
18 Mar-02:50:32 Re: collection from dany mabillard (Dany Mabillard)
17 Mar-01:57:58 Re: collection of volkmar stingl (Volkmar Stingl)
15 Mar-14:27:47 Re: collection of philippe durand (Philippe Durand)
15 Mar-13:49:04 Re: collection of firmo espinar (Firmo Espinar)
15 Mar-09:18:42 Re: collection of michael shaw (Michael Shaw)
15 Mar-03:45:43 The mizunaka collection - rhodochrosite (Am Mizunaka)
14 Mar-21:29:31 Re: monthly mineral chronicles, mineral guides and more... (Crocoite)
14 Mar-14:47:27 Re: collection of philippe durand (Jordi Fabre)
14 Mar-13:56:01 Re: collection of philippe durand (Philippe Durand)
14 Mar-11:24:43 Re: collection of philippe durand (Jordi Fabre)
14 Mar-08:55:22 Re: collection of michael shaw (Michael Shaw)
14 Mar-08:44:47 Re: the mim museum in beirut, lebanon (Mim Museum)
14 Mar-07:24:12 Re: collection of volkmar stingl (Volkmar Stingl)
14 Mar-02:30:15 The mizunaka collection - quartz (Am Mizunaka)
14 Mar-02:20:37 Re: collection of volkmar stingl (Tobi)
13 Mar-23:40:08 Re: collection of volkmar stingl (Volkmar Stingl)
13 Mar-14:22:58 Re: don lum collection (Don Lum)
13 Mar-14:02:43 Re: collection of philippe durand (Philippe Durand)
13 Mar-00:57:48 The mizunaka collection - quartz (Am Mizunaka)
12 Mar-07:36:06 Re: can you recommend a lab to analyse specimens (Luiz Oliveira)
11 Mar-16:19:18 Re: collection of philippe durand (Riccardo Modanesi)
11 Mar-15:18:26 Re: collection of philippe durand (Philippe Durand)
11 Mar-15:13:07 Re: collection of philippe durand (Philippe Durand)

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
111632


The time now is Mar 19, 2024 06:16

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.
Black stones
  
  Index -> FOR BEGINNERS: What is it? Where is it from?
Like
2


View previous topic :: View next topic  
Author Message

Marjolein van Braak




Joined: 28 Aug 2021
Posts: 10

View user's profile

Send private message

PostPosted: Aug 28, 2021 06:35    Post subject: Black stones  

I am not really sure about those 2 stones. My 2 guesses are black hornblende or black tourmaline, but it could be that I am wrong, black stones drive me crazy at times. I also have no clue where those two pieces come from. In the bigger piece you can sometimes see an orange (and a little rainbow) shimmer.

P.S. I just have a box with around 50 pieces of crystals and rocks that I don't know names or locations of. So.. be prepared there will follow some more posts.



WhatsApp Image 2021-08-28 at 13.34.49.jpeg
 Description:
 Viewed:  3219 Time(s)

WhatsApp Image 2021-08-28 at 13.34.49.jpeg


Back to top
Reply to topic Reply with quote
Like
   

James Catmur
Site Admin



Joined: 14 Sep 2006
Posts: 1336
Location: Cambridge


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Aug 28, 2021 06:45    Post subject: Re: Black stones  

We are very happy to help, but could you please do a few tests before each post as that helps more than photos

Tests 7 and 8 would really help you.

I suspect you will find the hardness of the 2nd specimen is 7 to 8, and if it is you may well be looking at Black Tourmaline ('Schorl'). Hornblende is softer (5 to 6). Does it scratch quartz (i.e. it is harder) or is it scratched by quartz (i.e. it is softer).

The streak will not help you as much as the hardness with these two minerals

https://www.mineral-forum.com/message-board/viewtopic.php?p=19487#19487
Back to top
Reply to topic Reply with quote
Like
   

Marjolein van Braak




Joined: 28 Aug 2021
Posts: 10

View user's profile

Send private message

PostPosted: Aug 28, 2021 07:14    Post subject: Re: Black stones  

Thank you for the reply, the hardness of the second specimen is indeed about the same as quartz. The second one is a little bit harder to determine, but I think it is also approximately the same. Quartz is maybe a little bit harder. So that would conclude that those both are tourmaline or schorl as you stated.

Is there maybe another mineral that it could be, that I overlooked?
Back to top
Reply to topic Reply with quote
Like
   

James Catmur
Site Admin



Joined: 14 Sep 2006
Posts: 1336
Location: Cambridge


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Aug 28, 2021 09:21    Post subject: Re: Black stones  

If the second one in harder than quartz, then tourmaline is likely. For the first, which is less hard than quartz, it is unlikely.

Check their streaks as that may help a bit
Back to top
Reply to topic Reply with quote
Like
   

John Betts




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

View user's profile

Send private message

PostPosted: Aug 28, 2021 10:07    Post subject: Re: Black stones  

They are most likely black tourmaline. Probably schorl.
_________________
John Betts
Back to top
Reply to topic Reply with quote
Like
2
   
Display posts from previous:   
   Index -> FOR BEGINNERS: 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