Thought it was green algae, turns out to be crystals

[Wint]

Found an interesting looking stone with what looked like algae on it, after attempting to clean it multiple times it never came clean. After looking at it through a magnifying glass turns out it’s a bunch of little green crystals. Some neat stuff, anyone know what it may be?

 

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[Steve1236]

Olivine comes to mind first but hard to tell from a picture, maybe a good shot of the host rock would help with identification...