The Brew Cabin

So I've been cleaning exterior areas for 10years. Recently I seem to have come across more sandstone and limestone with the green staining. Now it's not algae and it can only be described as a form of oxidisation/green patina similar to that found on copper pipes, but deep within the stone.

Now naturally you scour the area looking for any obvious culprits, metal furniture etc. There is however none on this patio.
I have spoken to various people with various answers, ranging from oxidisation to deep rooted lichen. I can't seem to work out how to add pictures if possible so any help there would be great to start. The green staining does lighten slightly when the slabs are dry, but looks pretty bad when wet.
So here I am reaching out to see if anybody can shed some definitive light on what this is and if its possible to remove.
Thanks in advance

To post images you will first need to upload them to an image sharing site see https://expertphotography.com/best-free-image-hosting/

then enclose the URL of the shared image within the []IMG tags - clicking the 'Inser IMage' button will do this for you

e.g., the URL for the imgBB logo is

https://simgbb.com/images/logo.png

So I'll enclose it with IMG /IMG (including square brackets) so that it shows up here:

See

viewtopic.php?t=11197

Let's see if this works, I've used imgbb and the links it gave me. Maybe they are too big for the site layout, as they were taken on my phone.






https://ibb.co/LYJWdYH
https://ibb.co/Vvm5Wj7
https://ibb.co/nrGNRnh
https://ibb.co/XYkdv0W

I suspect that you've used the complete page in your IMG tags rather than the direct image URL -if you right-click on one of your images on the img.bb page then you can "open image in new tab" - this new tab should give you the direct URL, e.g. your first web page gives:

https://i.ibb.co/HBxsTB3/20230503-112438.jpg

Which, when sandwiched in the IMG tags give:

Thank you, I appreciate your time to explain.
I'll try and amend the post.