Scainiite is a very rare lead-antimony sulfide. The mineral was known only in a few, poor specimens from this locality until recently (I am told these were collected in 2009), as you can see from the few photos of smears on a rock, shown on MINDAT. Even at its type locality, 3 mm crystals would be considered large. Here you have, however, 7 cm-long carpet of flatlaying crystals on matrix. They are embedded, and grown in aggregate, but still are huge examples of the species and this is one of the more rich specimens recovered.