Formula: Cu(Y,REE)₄(CO₃)₄(OH)₅Cl · 2H₂O

Species: Carbonates

Colour: Bright royal blue to pale blue

Lustre: Vitreous, Pearly

Hardness: 4

Specific Gravity: 3.64

Crystal System: Monoclinic

Name: Honouring Robert James Champion de Crespigny (b. 1950), Chairman of Normandy Mining Ltd. and Chairman of the South Australian Museum, for his contributions to Australian education.

Type Locality: Paratoo copper Mine, Peterborough, South Flinders Ranges, Flinders Ranges, South Australia, Australia