Several opaque, partial to well-formed roughly octahedral dolomite crystals in a tabular gypsum matrix, with the largest individual measuring 9 mm. This dolomite variety is iron-rich - (Ca,Mg,Fe²⁺)CO₃. Typical for the species/locality. Could probably be trimmed to a thumbnail with minimal loss, but I would be concerned about such trimming dislodging the dominant crystal.