Sousou no Frieren - Vol. 7 Ch. 61 - Magic Sealing Crystal

[AngelHQ]

Maybe they don't have the tech to do it without magic. Cause while they can have magic that can produce that pressure, the stone could block out the mana that might be embedded in the water to keep that pressure. Compared to the fire which could stay lit since it could be a fire starter spell and it stays due to the wood and not really mana.

Of course! High pressure water is hidraulic technology, 20th century stuff.

 

[WanArk86]

i dont get it if the crystals cant be cut then how do smaller chunks exist

Tectonic activity or glacier, maybe?

 

[Pietje013]

Mana sealing stones are too valuable to sell. The location of the mine even more