They don’t need to be built in active volcanoes like the one ring, they just need to be able to withstand the heat for a limited amount of time.
Your convent peaked my interest, so I searched for the temperatures of lava and molten steel. Turns out (and I didn’t expect this at all): lava is 700-1300°C, steel is 1300-1500°C. I expected lava to be somewhere around 2500-3000 °C, so i thought you would have to be quicker than foundry personnel. Instead, you would have even more time than with molten steel to get a cut of fresh lava straight from the vulcano and drink it.
They don’t need to be built in active volcanoes like the one ring, they just need to be able to withstand the heat for a limited amount of time.
Your convent peaked my interest, so I searched for the temperatures of lava and molten steel. Turns out (and I didn’t expect this at all): lava is 700-1300°C, steel is 1300-1500°C. I expected lava to be somewhere around 2500-3000 °C, so i thought you would have to be quicker than foundry personnel. Instead, you would have even more time than with molten steel to get a cut of fresh lava straight from the vulcano and drink it.