Montecchio Maggiore, Vicenza, Italy. Link to MinDat.org Location Data.
Name Origin:
Named after the German mineralogist and chemist, Christian Gottlob Gmelin (1792-1860) of Turbingen, Germany. Na modifier added by the zeolite nomenclature committee.
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Sacerdoti M , Passaglia E , Carnevali R , Zeolites , 15 (1995) p.276-281, Structural refinements of Na-, K-, and Ca-exchanged gmelinites, Note: sample 1Na
Brittle - Uneven - Very brittle fracture producing uneven fragments.
Habit:
Crystalline - Coarse - Occurs as well-formed coarse sized crystals.
Habit:
Druse - Crystal growth in a cavity which results in numerous crystal tipped surfaces.
Hardness:
4.5 - Between Fluorite and Apatite
Luster:
Vitreous - Dull
Streak:
white
Optical Properties of Gmelinite-Na
Gladstone-Dale:
CI meas= 0.009 (Superior) - where the CI = (1-KPDmeas/KC) CI calc= -0.03 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2382,KPDmeas= 0.2292,KC= 0.2312 Ncalc = 1.47 - 1.5