Gold.....!!!!??

[cyprusmax47]

I only can remember that there was no pyrites as it was a place where quartz is very common nearby. It is very hard and does not dissolve at all. It looks to me that the place is an abandoned asbestos mine...

Max

[ph06kg1]

Is this like your white one Max?

I have seen similar in sulphur mines surrounding pyrite, but that stuff disolves to the touch whereas this stuff withstood the scrubbing brush I just used on it.

No green stuff though.

There was a lot of this white stuff where I found it.

Stop me if I am getting too technical.
 
huh.jpg

This is a carbonate rock Dominic, i think we have almost the same rock:

DSC03701.JPG (221.48 KiB) Viewed 5180 times

These rocks form when small rivers (rich in calcium carbonate) flow and accumulate in ground holes, these aggregates are the result! I found mine in Yeroskipou area last year, near a small lake formed by river flow!

[MikeH]

Hi Max, thank you.

I am pleased to have found some other geologically-bent minds. I have at least one specimen to run under your eyes for comment (soon).

I think your specimens are good for serpentine, at least on the surfaces shown. The greasy-greeny-streakyness is all good.

//Mike

[MikeH]

Dominic, you can check if your white mineral is carbonate by putting a drop of acid on it to see if it fizzes. How much fizz depends partly on the strength of the acid: vinegar might give a little, conc. HCl a lot (careful!)
White is probably the most common colour for minerals, and many of them occur in similar crystal forms, so it is easy to make wrong guesses.

//Mike

[MikeH]

Who's up on concretions in evaporites?
Especially pale lime-green ones in alabaster?...

I found these beside a country track between Polemi & Stroumpi.
I don't know exactly where (tut, tut!)

Any ideas on the mineralogy?

//Mike

[cyprusmax47]

It is Gypsum, Mike, 100%

Max

[MikeH]

I know the alabaster is gypsum (barely a bubble with 30% HCl).

But what about the concretions?
Ferrous sulphate / glauconite? / ???

I lean towards glauconite. Note "a diagnostic mineral indicative of continental shelf marine depositional environments with slow rates of accumulation" and "Glauconite forms under reducing conditions in sediments and such deposits are commonly found in nearshore sands, open oceans and the Mediterranean Sea" [https://en.wikipedia.org/wiki/Glauconite]

[MikeH]

I should add that the original pale lime-green colour has faded somewhat.
It is nothing to do with the superficial algal green colouration seen in some of my photos.

[ph06kg1]

Yes I agree, it is alabaster gypsum as you noted! This kind of concretions is very common; in Maroni basin for example they are attached to alabasters in the same way. I would guess it is just gypsum that didn't get the chance to crystallize. Or, it might be carbonate calcium! Supersaturated (Ca, C) hot streams of water can create such type of concretions. In case that it's not crystallized, HCL can even face a large fizzing - difficulty!

Regards, George

[cyprusmax47]

Another funny looking example from the same area (fossilized frog )





Max

[MikeH]

Thank you, guys.
(love the fossilized frog!)

Having done more research online...
There is an interesting discussion on Cypriot evaporites in John K. Warren's excellent 'Evaporites: A Geological Compendium', around pp.469-476)
https://books.google.com.cy/books?id=8e ... us&f=false
It mentions Polemi, and it does mention nodules and concretions (mainly re anhydrite/chert), but it does not mention glauconite

In your photo especially, Max. judging by the similar weathering of concretion/host, I think chert is unlikely, and I wonder if the concretion is either:
- just an iron-enriched volume of alabaster (greenish due to the iron being in a Fe2+ state), or
- iron sulphate, which is "most commonly encountered as the blue-green heptahydrate" [https://en.wikipedia.org/wiki/Iron(II)_sulfate].
Iron sulphate heptahydrate is FeSO4·7H2O
Gypsum is CaSO4·2H2O
Give/take some water flexibility, the reaction FeO + CaSO4 = FeSO4 + CaO is balanced. So I am quite liking the iron sulphate hypothesis.
I think that would also account for the distinct outline of the concretions better than Fe+ as a partial substitute in the CaSO4 structure which gives the diffuse brownish Fe3+ colours sometimes seen in alabaster.

[cyprusmax47]

Interesting Mike. Next to that rock with the "frog" I photographed also a interesting formation which looks to me alabaster in the center....



Max

[MikeH]

Yes Max - alabaster and siltstone intercalations