Amygdaloidal cavities in basalts and similar rocks. Redefined from stilbite by IMA zeolite committee.
IMA Status:
Valid Species (Pre-IMA) 1801
Locality:
Ha�y mentioned occurrences in Iceland, Andreasberg in Harz, Alpes Dauphinoises and Norway, but no clear type-locality. Link to MinDat.org Location Data.
Name Origin:
From the Greek stilbe - "luster" in allusion to the pearly to vitreous luster. Ca modifier added by zeolite committee.
Globular - Spherical, or nearly so, rounded forms (e.g. wavellite).
Habit:
Wheat Sheaf - Bundle shaped aggregates resembling wheat sheafs after hand reaping wheat.
Hardness:
3.5-4 - Copper Penny-Fluorite
Luster:
Vitreous - Pearly
Streak:
white
Optical Properties of Stilbite-Ca
Gladstone-Dale:
CI meas= 0.019 (Excellent) - where the CI = (1-KPDmeas/KC) CI calc= 0.042 (Good) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2235,KPDmeas= 0.2287,KC= 0.2332 Ncalc = 1.49 - 1.51
Optical Data:
Biaxial (-), a=1.479-1.492, b=1.485-1.5, g=1.489-1.505, bire=0.0100-0.0130, 2V(Calc)=76-78, 2V(Meas)=22-79. Dispersion weak, r < v.
Calculated Properties of Stilbite-Ca
Electron Density:
Bulk Density (Electron Density)=2.19 gm/cc note: Specific Gravity of Stilbite-Ca =2.15 gm/cc.
Fermion Index:
Fermion Index = 0.01 Boson Index = 0.99
Photoelectric:
PEStilbite-Ca = 2.00 barns/electron U=PEStilbite-Ca x rElectron Density= 4.36 barns/cc.
Radioactivity:
GRapi = 0 (Gamma Ray American Petroleum Institute Units) Stilbite-Ca is Not Radioactive