I was looking in experimental and I saw an option for CAVES and CLIFFS so I turned it on I looked at cave generation for a bit and then looked at some mountains and saw 2 vain of emerald a 5 vain and an 8 vain! So i looked around for a bit and found many more

i think this is just a bug to do with amount of ore but now emerald ore is not rare at all!

I added an image of my findings below 👇 NOTE I USED X-ray AND A command block to get ride of stone this is not what the mountain looked like

i don’t know if this is a problem with other ores