Gault & Waller (1980): "Microprobe analysis of one crystal indicated the U:Th ratio to be 13:1, slightly higher than most uraninites of Grenville pegmatites and calcite dikes (Robinson & Sabina, 1955). The only compositional zoning detected was a slight increase in calcium content from the core to the outer edge."
Habit:
Gault & Waller (1980): "Uraninite occurs as single and interpenetrated octahedra up to 7 cm. Although some crystals are perfectly equant, many are flattened on {111}. Many of these flattened octahedra are interpenetration twins along the [111] axes (fluorite law). The cube {100} and trapezohedron {114}, alone or together, are occasionally found modifying the octahedra."
Chaput-Payne Mine, Gatineau Park, Gatineau TE, Outaouais, Québec, Canada