This week’s Facebook Mineral of the Week Group’s selected theme is epitaxy!
But what is epitaxy, you might ask.
Epitaxy, with its prefix "epi" meaning "on top of," is a fascinating 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.
Epitaxy occurs naturally in the mineral world, where one mineral can grow on another with a specific alignment of their crystal lattices.
It was not all that easy to find specimens in my mineral collection that exhibit this phenomenon, as I don’t have it as a tag. Fortunately however, a text search did pick up a few specimens with epitaxy in the description. The one below is one of them. Here, colourless albite is growing epitaxially on orange orthoclase feldspar.
It would have been easier to photograph had the top surface been so afflicted! 😆
Below: Albite epitaxially grown on orthoclase, with smoky quartz, Glenrowan, Victoria. Width of view 6mm.
Epitaxy is common with sulphide mineral occurrences such as Madam and Panasqeira.