Formula: NaCaCu₅(AsO₄)₄Cl · 3H₂O

Species:

Colour: Sky blue

Lustre: Vitreous

Hardness: 2 – 3

Specific Gravity: 3.78

Crystal System: Tetragonal

Name: Named for Chester (Chet) S. Lemanski, Jr. (b. 1947), a New Jersey, USA, collector and former President of the Franklin-Ogdensburg Mineralogical Society, board member and former Vice President of the Franklin Mineral Museum, former hard rock miner (Sterling Mine, NJ) and professional investigator, now retired.

Type Locality: El Guanaco Mine, Taltal, Antofagasta Province, Antofagasta – Chile

Dimorph of: Lavendulan

Masses and aggregated groups of crystals in and on matrix; massive, filling spaces between breccia fragments. Easy to confuse with lavendulan, with which it may occur simultaneously.