The chemical composition of mineral Calcioandyrobertsite-2O is indicated by the formula KCaCu5(AsO4)4[As(OH)2O2]•2(H2O). This mineral is commonly found occuring in a specimen of quartz gangue. Calcioandyrobertsite-2O is a polymorph of calcioandyrobertsite structure. Mineral Calcioandyrobertsite-2O is most commonly found at its type of locality at Tsumeb mine, Namibia. This mineral was named as the -2O polytype of calcio-andyrobertsite-1M. Mineral Calcioandyrobertsite-2O is known to crystallize in the orthorhombic system of crystal formation. In optical mineralogy, this orthorhombic crystal system comprises crystals having three mutually perpendicular axes, of which all are of different lengths.

Calcioandyrobertsite-2O is commonly found showing good cleavage in one direction when evaluated under petrographic polarizing microscope used in the field of optical mineralogy. Calcioandyrobertsite-2O is most commonly found Intense Blue in hand sample. The specific gravity measure of the mineral is usually found 3.9 grams per cubic centimeters. Most crystals of mineral Calcioandyrobertsite-2O are found transparent in appearance. Calcioandyrobertsite-2O is commonly found showing conchoidal fracture when viewed under polarized microscope for mineralogists. This is usually developed in brittle materials characterized by smoothly curving surfaces. The crystal habit of the mineral as described in the field of optical mineralogy usually includes platy sheet forms when viewed under petrographic polarizing microscope used in the field of optical mineralogy. The hardness measure of the mineral is usually found ranging from 3 to 4 when evaluated using the Mohs scale method. Mineral Calcioandyrobertsite-2O is most commonly found showing vitreous or glassy luster when viewed under polarizing microscope used in the field of optical mineralogy. Mineral Calcioandyrobertsite-2O is most commonly found leaving a pale blue streak when rubbed on a white porcelain streak plate. Mineral Calcioandyrobertsite-2O is usually found showing biaxial negative figure when evaluated under petrographic polarizing microscope used in the field of optical mineralogy. Calcioandyrobertsite-2O is also commonly found showing 0.0200 birefringence. Calcioandyrobertsite-2O has a barely detectable radioactivity.