Near the top of this unit is a zone of brecciated scoria, slag-like basalt containing numerous amygdules, all less than 2.5 cm in diameter.
It contains numerous small pipe amygdules lined or totally filled with albite and calcite.
The presence of gonnardite in amygdules
is problematic, however, a limited substitution of Ca for Na in natrolite was registered.
The amygdules are generally filled with white minerals, and give the dark, brownish gray rock a spotted appearance.
Sabina (1992) lists it as "garronite (Na)." The mineral was found as a transparent, yellow to orange crystalline filling in amygdules 2-5 mm across, in a dark sill rock with a spotted appearance (A.