Assertion: lava's composition | /r/HasProperty | 2–6 wt% total alkalis
Facets:
Source sentences:
text: Basalt generally has a composition of 45–55 wt% SiO 2 , 2–6 wt% total alkalis, 0.5–2.0 wt% TiO 2 , 5–14 wt% FeO and 14 wt% or more Al 2 O 3 .