Post by: Sunandsand123 on 08/03/2019 12:02:09
53179982_10156130166386765_7968750658775941120_n.jpgI live in Saudi Arabia and we went out in the desert to look for Sand Roses and I don't know much about them...
We found a fair few, but some of them are crumbling...do they last? How long? How can I keep them forever intact?
I seem to have read that they are made from Gypsum or Baryte and that the gypsum ones tend to be more fragile..I washed the sand off of them and so did my friend. I know because there is mineral in it and that these types of rocks might be "alive" and therefore transform with time, with weathering, light etc. But I want to keep my roses :/....can anyone help me?? Thanks in advance!
Post by: chris on 08/03/2019 13:25:53
Now we await the geologists @Bass who can actually tell us more about them!
Post by: evan_au on 09/03/2019 08:21:20
- So washing the sand out is probably not a good idea, as that will dissolve some of the mineral back into the water.
- Next time try blowing the sand out with a gentle flow of air...
See: https://en.wikipedia.org/wiki/Evaporite
Post by: Bass on 11/03/2019 18:59:53
Known as "desert roses", "sand roses" and "selenite roses", these are actually gypsum (calcium sulfate dihydrate- calcium sulfate with water molecules attached). These form in arid environments, and as you've discovered are very fragile.
Evan-au correctly pointed out that using water (hydrating) the rosettes will cause them to break down more quickly- so try to keep them dry in place where they won't be jostled around.
Barite (baryte) roses form from barite (barium sulfate) which tend to be both harder and more durable than gypsum roses.
Post by: Bored chemist on 11/03/2019 19:23:46
Something like this
https://www.marksandspencer.com/bell-jar/p/p60115718
(I have no sensible idea of the scale of your specimens or the bell jar- but they are available in many sizes.)
Post by: Bill S on 16/03/2019 19:21:13
Post by: Bored chemist on 16/03/2019 20:06:06
But it's also important to recognise that the crystals have water as part of the structure. If they dry out they will crumble to dust.
I'm not sure how dry that needs to be. Presumably, very dry- given that you find them in deserts.
Post by: Bill S on 16/03/2019 21:02:15
http://www.essexfieldclub.org.uk/portal/p/Geology+Site+Account/s/Wrabness+London+Clay+Cliffs+(part+of+Stour+Estuary+SSSI)/o/Wrabness+London+Clay+Cliffs+(part+of+Stour+Estuary+SSSI)
back in the days when it was possible to extract good specimens there.
Post by: Monox D. I-Fly on 05/06/2020 05:00:15
These appear to be members of a class of minerals called evaporites - formed by evaporation of water from temporary lakes, leaving behind crystals of the minerals that were previously dissolved in the water.
- So washing the sand out is probably not a good idea, as that will dissolve some of the mineral back into the water.
- Next time try blowing the sand out with a gentle flow of air...
See: https://en.wikipedia.org/wiki/Evaporite
So... To put it in Layman's Terms, they're Desert Salt?