Basalt is a dense, extrusive igneous rock that forms at or near the earth’s surface as a lava flow rich in iron and magnesium rapidly cools. Cinderite is a scoria, which can have a similar mineral composition of basalt, but contains many vesicles that form as gases escape the cooling lava flow or ejecta.
As a soil amendment, the scoria (Cinderite) is superior at retaining moisture and nutrients and releasing trace minerals.