Brittle - Generally displayed by glasses and most non-metallic minerals.
Habit:
Aggregates - Made of numerous individual crystals or clusters.
Habit:
Radial - Crystals radiate from a center without producing stellar forms (e.g. stibnite)
Luster:
Vitreous (Glassy)
Streak:
white
Optical Properties of Lokkaite-(Y)
Gladstone-Dale:
CI meas= 0.047 (Good) - where the CI = (1-KPDmeas/KC) CI calc= 0.047 (Good) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2033,KPDmeas= 0.2033,KC= 0.2134 Ncalc = 1.62