Lévyne Sandwich

Mineral Matters #403

A little while ago, Richard Gibson posted about a wulfenite sandwich in his Geologic Column substack. In his post, he notes that the “sandwich” isn’t really a central layer surrounded by two outer layers of orange “bread,” but is rather just a band on the surface around the centre.

This lévyne specimen certainly is. It consists of a lévyne filling in two slices of erionite bread. The silky erionite crystals are growing perpendicular to the lévyne crystal faces. This type of growth is called epitaxy. You can find some other examples here.

Epitaxy is described as a process in crystal growth where new crystalline layers are deposited in a controlled manner on top of an existing crystal (substrate). These newly deposited layers, called epitaxial films or layers, inherit the crystalline structure and orientation of the underlying substrate, leading to well-defined, ordered growth.

This specimen also almost fits this week’s Facebook Mineral of the Week Group’s selected theme of crystals impaled or perched on another, but that is probably pushing it a bit! 😆

Lévyne is also the Mineral Snippet theme for the next issue of the Monthly Mineral Chronicles, out in the middle of August.

Below: Erionite on lévyne, Adel, Lake Co., Oregon, USA. Width of view 6mm. Click on the image for a higher resolution version.