An exceptionally rich example of nikishcherite, with numerous ball-like aggregates of the mineral on matrix.  A number of the balls have some shearing, as if they grew in something of a seam and some of the tops were touching the opposite rock face.  Regardless, this is an exceptionally rich example of this mineral-- especially considering the  vast majority of known specimens are just single, matrixless orbs.

Also of note, are a few green vivianite crystals on the matrix.

Because of the color of the nikischerite and of the matrix, the balls can be a bit harder to see in the pictures-- the image taken from an angle close to the display surface of the piece better shows the relief of the nikischerite orbs. 

This species is the iron rich analogue of shigaite, and was first described in 2001 from specimens produced during a single find that occurred in 2000.  At the time, there were estimated to be fewer that 200 specimens in existence— this recent find only bumps that up by a very small number. 

Virtually all of what was found in the original discovery back in 2000 were thumbnails. most without matrix.  To have a specimen of this size with this much nikischerite on it is virtually unheard of.