Could be a top of the line Brandtite originally from the Natural History Museum of Stockholm. See the prov. tab for older labels. The crystals are prismatic looking and published data call these forms prismatic, but truly they are more tabular (2/m) and occur in singles or in multible duplications producing sheaf-like bundles which only look striated and prismatic. The one crystal which is a single on this specimen is 4mm while the "prismatic" groups are 6mm. The single crystal is suspect since is is so unlike the others on this specimen. Superb specimen of this rare mineral.