Slender prismatic epidote crystals across quartz, each one grooved along its length.
Those grooves are the quickest way to recognise epidote. They run parallel down the long axis of every crystal, they are a product of how the mineral stacks internally rather than any kind of wear, and almost nothing else green forms slim striated prisms like it.
Worth a loupe. The striations show up far better magnified than they do in a photograph.
Mineral: Epidote (calcium aluminium iron silicate) with quartz (silicon dioxide, SiO₂)
Crystal system: Epidote monoclinic, quartz trigonal
Origin: Hakkâri Province, Turkey
Hardness: 6 to 7 on the Mohs scale; durable overall, though slender epidote crystals snap if knocked
Treatment: None
Dimensions: 10.7 x 5.6 x 7.8 cm
Weight: 505 g
You will receive the exact piece photographed.