A base of blocky, transparent selenite gypsum crystals is partially coated by a second generation of contrasting, white sugary gypsum. A few sparse patches of red metastibnite can be see withing the clear gypsum crystals. Metastibnite, a simple antimony sulfide - Sb₂S₃ is an uncommon dimorph of the more familiar stibnite (also Sb₂S₃).