Pietra di Luserna is a “Gneiss”, a lamellar metamorphic rock formed by a set of overlapping layers, extracted between Val Pellice and Valle Po, in central-western Piedmont, in the Cottian Alps.
Its formation seems to date back to the transformations of an alpine rock of volcanic origin which took place between 130 and 65 million years ago.
It is mainly made up of white mica, feldspar, quartz and green mica: depending on the percentages of these components, the stone takes on different colors ranging from mixed grey, i.e. a more or less dark gray with golden veins, to selected grey, i.e. a gray softer and more compact without veins, always blue-green on a greyish base.
The gray base is due to the feldspar which is present in greater quantities than the other components and gives the stone this colour.