Rock id??

[Nourhan22]

Hello! I found these beautiful rocks on etsy. The seller claims they are sandstones but others have told on other forums that some are not in fact sandstone. Can I please get id's for these rocks. They are two different sets. Thank you! I would also like to know if this is in fact sandstone, is it safe to use for aquariums? I jave heard mixed reviews on this and would like to get a different opinion.

[Autumnsky]

The rocks are varied. Not Sandstone per se.

Pic 1
rock
1 Red river rock looked up and said likely Granite
2 The second looks like Chalcedony or Chalcedony with Agate, very nice looking.
3 Schist - a metamorphic rock
similar bottom pic right
https://flexiblelearning.auckland.ac...ks/schist.html

Pic 2
rock
1 Can't tell but could be a river rock, just can't see it well enough
2 maybe Black Limestone With White Calcite Veins, can't quite tell since it looks shiny with water
3 Possibly Flagstone which is sandstone the black parts could be lichens

More info for learning about the main rock types
https://www.usgs.gov/faqs/what-are-s...ience_products

https://www.usgs.gov/faqs/what-are-i...ience_products

https://www.usgs.gov/faqs/what-are-m...ience_products

[Nourhan22]

Thank you very much for information! I probably don't trust this seller cause they claimed it was all sandstone. Plus I don't things like granite leaching into my aqaurium. I took a geology class in college but am a little rusty. I think I'll stick to rocks from pet stores which are safer. I just love the colors on those stones it's a shame that they can't be put in aquariums

[Autumnsky]

Dragon stone or Ohko stone. My understanding is they don't alter water hardness.

[Autumnsky]

Seiryu rocks can be sold at the fish store but they can raise the pH. Can be manageable in a tank with routine water changes, unless you have high pH already.

So double check what kind of stones are offered and double check whether they change the water pH.