Pseudo-cubic? Optically biaxial.
G = 4·017. H = 51⁄2. Yellow; transparent to opaque.
The Urals; Switzerland; Tyrol, etc.
Pilbarite.
PbO,UO₃,ThO₂,2SiO₂,2H₂0 + 2aq. ThO₂ = 31·3%. Cer and Yttr—traces.
Amorphous.
G = 4·4-4·7. H = 21⁄2-3. Bright yellow; opaque.
Pilbara goldfields, West Australia.
Pitchblende.
A mixture of oxides, chiefly UO₂ and UO₃, but without E₂O₃ or ThO₂.