What is this stone?

Anna

***update***

I just had someone look at it, and it is indeed malachite! I have a friend who has done a lot of work with Native American jewelry. This is a very old piece, but she said it’s malichite, and based on its pattern, I would agree! Thanks everyone!!!

I’ve been trying to figure out what this stone is. This ring was my grandmother’s, maybe my great-grandmother’s, but it was put away in some jewelry she never wore. I have two others, one that’s obviously turquoise, and one that’s pink quartz. This one has almost a petrified wood pattern, but it’s green. It could theoretically be acrylic, but I doubt it given the rest of the jewelry it was with. The setting is silver, but it’s old, so it’s hard to see the mark.