Having a low water content when newly formed typically less than 1% water by weight, becomes progressively hydrated when exposed to groundwater, forming perlite.
Ukuba nokuqukethwe kwamanzi aphansi lapho kusanda kwakhiwa, imvamisa kungaphansi kwe-1% lamanzi ngesisindo, i-obsidian iba manzi ngokuqhubekayo lapho ivezwa emanzini angaphansi komhlaba, yakha i-perlite.