Pele's tears 
(tîrz)
(tîrz)pl.n.
Small, tear-shaped or nearly spherical pieces of volcanic glass often found at the end of a strand of Pele's hair, forming from the solidification of lava droplets ejected from a volcano.
[Translation of Hawaiian waimaka o Pele : waimaka, tears (from wai, water + maka, eye) + o, of + Pele, volcano goddess (from pele, lava flow).]