Dennerle Crystal Quartz gravel and Corydoras.

[Rabid Raisin]

Hi hive mind.

I've got Dennerle Crystal Quartz Diamond Black in my tank and had concerns it was too rough for Corydoras, however, I've just dug the bag out and it says safe for Corys (sharp edges are rounded off). [bag pic below]

Dennerle are a big enough company that I sorta trust what they say, but has anyone had problems? either with Corys or fish that pick a lot at the substrate getting mouth problems? (barbs for instance).

Second picture shows grain size compared to a UK penny (21mm dia).
Does anyone know how this grain size and shape compares to pool filter sand?

thanks RR

[DoubleDutch]

In fact it is the same stuff as PFS. 
Won't be a problem

Verstuurd vanaf mijn SM-G925F met Tapatalk

[Vale!]

Bzzzzz...


It's splendid for Corys etc. - I used it for years in my South American phase, and still do now that I've crossed the Pacific, as it were. I had a conversation with Dennerle about it a couple of years ago so I know more about it than is offered by the bag. In which connection ...




Your second pic sent a shudder down my spine ; it reminded me of an unresolved mystery and the apparent closed-mindedness of the mineralogical community!




[Edit: to acknowledge DD's interposed post.  Hi Aaad!]

[Rabid Raisin]

Thanks DD and Vale!

Vale! was the "unresolved mystery" the black crystals? I had some thoughts about that - will see if I can find the info I was looking at.

[Vale!]

Yes, indeed it is!


I look forward to reading your thoughts about it in due course.

[Rabid Raisin]

Vale!
Ah "puzzlement" it all came rushing back from when I first read it :o

I don't have an answer unfortunately as I only did geology at "A" level and crystallography was my worst bit, but a couple of thoughts and hopefully some pointers as "puzzlement" niggled me a few times over the last year;

A lot of minerals can be formed by bacteria living in an anoxic environment with access to metals and nitrate, all of which can occur in your gravel.

This means you might be better off talking to a soil scientist rather than a geologist, as it's possible your minerals are transitory to another form over the geologic time scale.

Biogenic Mineral Formation is the term to google.
This abstract gives a flavour of what I'm thinking
http://adsabs.harvard.edu/abs/2014AGUFM.B41H0147P

https://en.wikipedia.org/wiki/Vivianite no Si though. Have a look at the section 'geological setting' to get another idea.
Also look at the variety of minerals within the Vivianite itself.

I initially thought of magnetite but that was too simplistic, however, magnetite/iron compounds can be formed by biogenesis, so have a read of the last paragraph of this article before deciding whether to read the rest ;D
http://aem.asm.org/content/67/6/2844.full

My geology knowledge is more fossil/rock formations based but it does mean I've seen lots of metal banding in places like Lyme Regis which has lots of fossils in part because the cliffs are composed of shales and mudstones which formed in tidal lagoons which occasionally became anoxic and killed all their inhabitants.

Unfortunately I think this science is fairly new and only really came to the fore when 'Black Smokers' were studied, and prior to that most metals were considered precipitates, not biogenic.

I may be way off base here, but possibly a line to follow.

A streak test may discount some minerals, rub a crystal on a white unglazed tile and look at the streak colour (in daylight) - probably white, but you never know ;D

edit; spelling as always.