There are many variations of these faces but the flattened blades and tabular crystals are the most common. If the pinacoid faces become diminished or are absent, the resulting prismatic crystal has a rhombic cross section. This habit is rather common in specimens from Madagascar. Also nodular, fibrous or granular. Cleavage is perfect in one direction, less so in another direction.
Fracture is conchoidal.
Streak is white. Associated Minerals are calcite , gypsum , strontianite , sulfur and fluorite . Best Field Indicators are crystal habit, color and flame test.