One of the two places to find Green Gems on Fjordur, is the Hidden Grotto cave (36 LAT, 37 LON). It’s a normal cave that can only be accessed by swimming through a secret underwater area. It’s very deadly though, A LOT of Aberrant Megalosaurus and Aberrant Megalanias. The underwater entrance itself is guarded by loads of Megalodons. -KD
ok so to get this you can either mine it yourself or if not on your map go to a map with this and mine it then put it in the obelisk item tab, go to obelisk on your map and grab it. (to do this there is a items tab in the terminal that you can put stuff in so for reference you can get cactus sap on the island, there is also a tab for creatures. they just need to be on the terminal and then you can put them in, note this will remove saddle and inv. so you can crypod them instead for them not to, just note you cant put crypoded creatures in the creature tab) or find a roll rat and steal the gems. it will get mad after you steal the gems, so run or fight. up if helpful.
In aberration they fall from the ceiling during earthquakes, and are easy to find all around the portal area. They have a glow to them so they should be easy to spot. Watch out for basilisks, they spawn near the portal area (and ARK said that was the easiest spawn point 😤😤😤)
There seems to be no blue gem option so I'm putting this here. There are trees with white leaves in the wasteland that give blue crystallized sap, which is a replacement for blue gems. I don't know the most effective harvest method, but the wyvern's wing attack seems to do good.
Blue Gems in Aberration are harvested with pick/axe @ LAT:54.4 LON: 32.4. They are in two forms; a sapphire blue resembling gacha crystals, and pillar crystals that are an aquamarine color. You'll find metal in abundance there, too.
For the guy who asked the question.On extinction gachas will give you crystallized sap which is used as a alternative to gems or just normal gems in big quantity too.You can also farm crystallized sap from the trees on extinction , in waste land.