Common zeolite in volcanic rocks, ore veins, diagenetically altered rhyolitic vitric tuffs, saline lake deposits, and ocean floor sediments. Shows solid solution toward harmotome.
IMA Status:
Approved IMA 1998 (Dana # Added)
Locality:
Capo di Bove, south of Rome, Italy. Link to MinDat.org Location Data.
Name Origin:
Named after William Phillips (1775-1829), English mineralogist and founder of the Geological Society of London. The K-dominant member of the phillipsite series.
Uneven - Flat surfaces (not cleavage) fractured in an uneven pattern.
Habit:
Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline).
Habit:
Pseudo Tetragonal - Crystals show a tetragonal shape.
Habit:
Twinning Common - Crystals are usually twinned.
Hardness:
4-5 - Fluorite-Apatite
Luster:
Vitreous (Glassy)
Streak:
white
Optical Properties of Phillipsite-K
Gladstone-Dale:
CI meas= 0.011 (Superior) - where the CI = (1-KPDmeas/KC) CI calc= 0.015 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.225,KPDmeas= 0.226,KC= 0.2285 Ncalc = 1.5
Optical Data:
Biaxial (+/-), a=1.483-1.505, b=1.484-1.511, g=1.486-1.514, bire=0.0030-0.0090, 2V(Calc)=70-72, 2V(Meas)=60-90. Dispersion r > v or r < v.
Calculated Properties of Phillipsite-K
Electron Density:
Bulk Density (Electron Density)=2.22 gm/cc note: Specific Gravity of Phillipsite-K =2.20 gm/cc.
Fermion Index:
Fermion Index = 0.01 Boson Index = 0.99
Photoelectric:
PEPhillipsite-K = 2.24 barns/electron U=PEPhillipsite-K x relectron= 4.97 barns/cc.
Radioactivity:
GRapi = 69.02 (Gamma Ray American Petroleum Institute Units)
Concentration of Phillipsite-K per GRapi unit = 1.45 (%)
Estimated Radioactivity from Phillipsite-K - barely detectable
Chemical Formula: 
- barely detectable