Field of View: 4.5 mm
Colorless hexagonal plates of levyne-Ca are coated with a very thin white overgrowth of offretite in vesicular Miocene basalt.
Photo by Rudy Tschernich
Lévyne-Ca the calcium dominated form of Levyne a zeolite mineral, i.e. a hydrated silicate mineral.
Offretite is a rather rare mineral. Member of Zeolite Group.
Alteration of basalt with the addition of potassium.