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
12 Dec-13:21:13 Re: the collection of pierre and riana joubert (Pierre Joubert)
12 Dec-12:45:07 Re: the collection of pierre and riana joubert (Philippe Durand)
12 Dec-09:43:21 Re: collection of michael shaw (Crosstimber)
12 Dec-09:00:41 Re: best labeling material for collection numbers on specimens (Peter Lemkin)
12 Dec-08:45:38 Re: collection of heimo hellwig (Heimo Hellwig)
12 Dec-07:31:11 Re: baryte collection of niels brouwer (Niels Brouwer)
12 Dec-07:00:24 Re: best labeling material for collection numbers on specimens (Peter)
12 Dec-06:41:06 Re: best labeling material for collection numbers on specimens (Herman Van Dennebroek)
12 Dec-05:39:42 Re: best labeling material for collection numbers on specimens (Stefan Koch)
12 Dec-05:18:42 Re: best labeling material for collection numbers on specimens (Peter Lemkin)
12 Dec-02:50:42 Re: the collection of pierre and riana joubert (Pierre Joubert)
12 Dec-02:35:40 Re: the collection of pierre and riana joubert (Heimo Hellwig)
12 Dec-02:11:01 Re: the collection of pierre and riana joubert (Pierre Joubert)
12 Dec-02:07:01 Re: best labeling material for collection numbers on specimens (Wendellwilson)
12 Dec-01:45:46 Best labeling material for collection numbers on specimens (Peter Lemkin)
11 Dec-20:05:45 Re: juan, spain. Help. (J. G. Alcolea)
11 Dec-19:40:16 Re: juan, spain. Help. (Montanpark)
11 Dec-18:37:37 Re: juan, spain. Help. (J. G. Alcolea)
11 Dec-18:07:16 Re: juan, spain. Help. (Joseph D'oliveira)
11 Dec-18:04:23 Re: juan, spain. Help. (Montanpark)
11 Dec-17:42:05 Juan, spain. Help. (J. G. Alcolea)
11 Dec-15:16:19 Re: new generation for picture - ploum (Ploum)
10 Dec-19:01:18 Re: don lum collection (Don Lum)
10 Dec-14:51:04 Re: the mizunaka collection (Am Mizunaka)
10 Dec-14:38:39 Re: the collection of pierre and riana joubert (Pierre Joubert)

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
48262


The time now is Dec 12, 2018 14:08

Search for a textSearch for a text   

A general guide for using the Forum with some rules and tips
Is this rock agate?
  
  Index -> What is it? - Where is it from?
Like
2


View previous topic :: View next topic  
Author Message

Jacqui Parsons




Joined: 16 Nov 2018
Posts: 4

View user's profile

Send private message

PostPosted: Nov 17, 2018 10:38    Post subject: Is this rock agate?  

Hi, forgive me if I'm in the wrong place, I'm new here. I've been trying to find someone that could identify some rocks that I've found and I've never found anyone yet, so please bear with me.
I found this lump of rock on the beach at Rhos-on-sea, Wales, UK. It's smooth to touch like agate. It's grey, white and purple stripes. Is it agate? Would it be worth cutting it into slices?



received_178882613061277.jpeg
 Mineral: Unknown
 Description:
Rhos-on-sea
12x6
 Viewed:  280 Time(s)

received_178882613061277.jpeg


Back to top
Reply to topic Reply with quote
Like
   

Jacqui Parsons




Joined: 16 Nov 2018
Posts: 4

View user's profile

Send private message

PostPosted: Nov 17, 2018 10:42    Post subject: Re: Is this rock agate?  

The other side of it


received_262025057795559.jpeg
 Mineral: Unknown
 Description:
Rhos-on-sea
12x6
 Viewed:  277 Time(s)

received_262025057795559.jpeg


Back to top
Reply to topic Reply with quote
Like
   

Kevin Schofield




Joined: 05 Jan 2018
Posts: 65
Location: Beacon NY

View user's profile

Send private message

PostPosted: Nov 17, 2018 11:41    Post subject: Re: Is this rock agate?  

Jacqui Parsons wrote:
The other side of it


Hi Jacqui.
Well, the first thing to say is that this is not an agate. In fact, it is not a mineral at all, but a piece of rock (although if my next guess is correct, it's a rock made mostly of one mineral!).

What you have is a piece of well-stratified (bedded) sedimentary rock. The prominent purple bed looks like a siltstone...similar to a sandstone, but with finer grains. All of the beds with the purple colouration have some of this silt in them. The purple colouration is characteristic of rocks deposited in an arid, desert-type environment (the purple is due to the presence of iron oxides). This gives a clue to the composition of the smooth grey and white striped portion of the rock. The combination of the colouration, the style of the bedding, some subtle features disrupting the bedding, and the possible association with an arid depositional setting suggest to me that this rock is made up mostly of anhydrite...a form of the mineral gypsum (or selenite) that commonly forms in arid, evaporative settings. If I am correct, the rock should also feel "heavy" compared to its size, as anhydrite is a relatively dense mineral. From where you collected it at Rhos, the most likely source are the Permian strata outcropping to the east around Rhyl.

_________________
Veni, Vidi, Emi
Back to top
Reply to topic Reply with quote
Like
1
   

Jacqui Parsons




Joined: 16 Nov 2018
Posts: 4

View user's profile

Send private message

PostPosted: Nov 17, 2018 12:55    Post subject: Re: Is this rock agate?  

Thank you Kevin. Yes it is very heavy for it's size, it weighs 1269gm. It was the only one of its kind I found on the beach apart from two small pieces right next to it which I assumed had come off the big piece.
Is it okay for me to post these questions about rocks I've found? I have quite a few which I pick up if they look unusual, I have quite a collection! They aren't as exciting or beautiful as all the fantastic pictures I've seen on here. Sometimes I buy them from a shop in Aberystwyth or off eBay. Most of them though I find in the river Severn, quartz rocks that have some remaining crystals hidden in the nooks and crannies.
Back to top
Reply to topic Reply with quote
Like
   

Kevin Schofield




Joined: 05 Jan 2018
Posts: 65
Location: Beacon NY

View user's profile

Send private message

PostPosted: Nov 17, 2018 13:16    Post subject: Re: Is this rock agate?  

Jacqui Parsons wrote:
Thank you Kevin. Yes it is very heavy for it's size, it weighs 1269gm. It was the only one of its kind I found on the beach apart from two small pieces right next to it which I assumed had come off the big piece.
Is it okay for me to post these questions about rocks I've found? I have quite a few which I pick up if they look unusual, I have quite a collection! They aren't as exciting or beautiful as all the fantastic pictures I've seen on here. Sometimes I buy them from a shop in Aberystwyth or off eBay. Most of them though I find in the river Severn, quartz rocks that have some remaining crystals hidden in the nooks and crannies.


Jacqui...yes, I think it is fine to post your questions here.This is a very friendly forum, and although it is aimed mostly at mineral identification, we are generally OK with rocks too...especially if you are trying to identify particular minerals that make up the rock. We generally ask you to do a little work up-front to help us along the way...easily made home measurements such as density (via weight, which would have helped here), hardness (does it scratch glass, can it be scratched by glass, or a steel knife). There is actually a little "how to" guide somewhere on the forum that will help you with that (I'm sure one of our very attentive site Admins will point the way!)

_________________
Veni, Vidi, Emi
Back to top
Reply to topic Reply with quote
Like
1
   
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 2006-2018


Powered by FMF