Does anyone know any guides that list the best monsters/areas to farm for specific ore/gems like mithril or garnet?
I don’t think any such guide exists. Farming ores is not an efficient way to earn money since their values are relatively low and their drop rates aren’t good enough to make it worthwhile. I think most people just save them up as they play or buy them. But if your heart is set on farming them, start with common leech mobs such as skeles, ulu1/ulu2, harps, ftp, etc. Whatever ores they drop, the best way to farm them is to just use aoe attacks. Theoretically, you could do the same with any small, easy-to-navigate map containing a lot of mobs. Forming LHC parties is a good way to get ores dropped by golems and bearwolves. Certain Party Quests (LPQ and OPQ, for example) and Orbis exchange quest etc items give ores too but it’s not very consistent or efficient. The best way to get steel is probably to hunt Iron Hogs and trade in their hoofs in Kerning. (100 hoofs = 1 Steel Plate)
unless you are doing ironman challange I dont think you should be farming those in general but there are some niches. steel you can farm from iron hogs (I think you can exchange their etc to steel too somehow (?)) and you can farm both steel and milthril on scorpion in ariant. generally you can use the wiki to find out everything that drops ores and figure out what the best one is https://royals.wiki/etc/material-mineral/4010002
The Mineral converter in Kerning will accept 100 Iron Hoofs (and 3000 meso?) for 1 steel plate or the normal 10 steel ore. There's a handful that come from highly farmed spots, that are farmed for reasons outside of farming for Minerals. But cost wise it's basically almost always better to just buy the minerals you need or farm for other reasons For Example Mage Farmers (Yetis & Pepe): Will have Garnets, Bronze, Diamonds, Orihalcon, Sapphire, Steel, and Power Crystals Skele Sellers Will have Wisdom Crystals, Amethyst, and Steel, Aquamarine, Topaz, and Dark Crystal. Harp Sellers will have Orihalcon, Sapphire, Gold, Diamond, Wisdom & Power Crystals Also when people do Orbis ETC to level up a char they get a good amount of ore that way. For example 114 rolls to get Garnet Ores, Amethyst Ores, Aquamarine or Diamond Ores from Yeti Horns. Honestly just about every ore is secondary to some farming method. For example, Bubbling farming (For really really low level players) is a decent place to get Mithril Ore or Mossy Mushrooms. The only one that is 'harder to find' is Emeralds. Maybe Qualm Monks, Nependeath Farmers, Rexton Farmers?