tektite
tek•tite \ˈtek-ˌtīt\ n [ISV, fr. Gk tēktos molten, fr. tēkein to melt – more at THAW] (1909) : a glassy body of probably meteoritic origin and of rounded but indefinite shape – tek•tit•ic \tek-ˈti-tik\ adj
Merriam Webster’s Collegiate Dictionary, 11th Edition