Discovered on a single, handsized sample of altered breccia (or possibly, altered marble) collected in the summer of 1985. Reyerite group; structure determined.
IMA Status:
Approved IMA 2002 (Dana # Added)
Locality:
Poudrette quarry, Mont Saint-Hilaire, Rouville County, Quebec, Canada. Link to MinDat.org Location Data.
Name Origin:
Named for Andre Edmond Lalonde (b. 1955), Professor of Geology at the University of Ottawa, Ottawa, Ontario, Canada.
Irregular Grains - Occurs as splotchy, anhedral crystals forming inclusions in other minerals or rocks.
Habit:
Subhedral Crystals - Occurs as crystals which tend to exhibit a recognizable crystal shape.
Hardness:
3 - Calcite
Luminescence:
Fluorescent, Short UV=violet-blue, Long UV=none.
Luster:
Pearly
Streak:
white
Optical Properties of Lalondeite
Gladstone-Dale:
CI meas= 0.003 (Superior) - where the CI = (1-KPDmeas/KC) CI calc= 0.007 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2097,KPDmeas= 0.2105,KC= 0.2112 Ncalc = 1.53