Diallage

[clarification needed][2] Diallage is typically an opaque mineral, but translucent specimens can occur.

Due to alteration, diallage can grow spots on its surface, which are made out of smaragdite (the green variety of amphibole).

When the crystal forms, there are secondary minerals, which are hydrated oxides, such as opal, goethite and limonite.

Thanks to these minute inclusions, the mineral reflects the light so that it creates a metallic luster, or the effect commonly known as "schiller".

[2] Without having proper equipment, diallage could be distinguished from other members of the class due to having a metallic luster and thin foliated structure.

[3] Diallage is commonly found in association with other members of the augite series within the clinopyroxenes, such as with fassaite.

It can also be found in the western region of the Alps, around Sondalo, however these specimens are generally lower quality ones.

These spots include Passo del Bracco, the mines of Acquafredda and Bargone, next to Sestri Levante.

Another occurrence is in the Tuscan-Emilian Apennines, in Sasso Puzzino and Serra del Zanchetto, near Bologna.

Mindat claims it is a variant since the parting is different,[1] while Wiktionary states that it is a green variety of pyroxene.