It occurs in open cavities up to several centimeters across and formed as a result of late-stage hydrothermal alteration of earlier formed Zr-bearing minerals.
IMA Status:
Approved IMA 1992
Locality:
Mount Mica granite pegmatite, South Paris, Oxford County, Maine, USA. Link to MinDat.org Location Data.
Name Origin:
In honor of the late Dean McCrillis and his son, Philip.
Name Pronunciation:
Mccrillisite + Pronunciation
Synonym:
IMA1991-023
Mccrillisite Crystallography
Axial Ratios:
a:c = 1:2.62893
Cell Dimensions:
a = 6.573, c = 17.28, Z = 2; V = 746.57 Den(Calc)= 3.35
Conchoidal - Fractures developed in brittle materials characterized by smoothly curving surfaces, (e.g. quartz).
Habit:
Crystalline - Fine - Occurs as well-formed fine sized crystals.
Hardness:
4.5 - Between Fluorite and Apatite
Luminescence:
Non-fluorescent.
Luster:
Vitreous (Glassy)
Streak:
white
Optical Properties of Mccrillisite
Gladstone-Dale:
CI meas= -0.092 (Poor) - where the CI = (1-KPDmeas/KC) CI calc= -0.017 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1909,KPDmeas= 0.205,KC= 0.1877 Ncalc = 1.59 - 1.63
Optical Data:
Uniaxial (+), w=1.634, e=1.645, bire=0.0110.
Calculated Properties of Mccrillisite
Electron Density:
Bulk Density (Electron Density)=3.14 gm/cc note: Specific Gravity of Mccrillisite =3.35 gm/cc.
Fermion Index:
Fermion Index = 0.03 Boson Index = 0.97
Photoelectric:
PEMccrillisite = 105.94 barns/electron U=PEMccrillisite x rElectron Density= 332.18 barns/cc.
Radioactivity:
GRapi = 0 (Gamma Ray American Petroleum Institute Units) Mccrillisite is Not Radioactive
Chemical Formula: 