Isle of Mull, Scotland. Link to MinDat.org Location Data.
Name Origin:
Grossular is from the Latin grossularia meaning "gooseberry." Hessonite is from the Greek hesson, meaning "slight" in reference to the smaller specific gravity.
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Physical Properties of Grossular
Cleavage:
{???} Distinct
Color:
Brown, Colorless, Green, Gray, Yellow.
Density:
3.42 - 3.72, Average = 3.57
Diaphaneity:
Transparent to subtranslucent
Fracture:
Sub Conchoidal - Fractures developed in brittle materials characterized by semi-curving surfaces.
Habit:
Crystalline - Fine - Occurs as well-formed fine sized crystals.
Habit:
Euhedral Crystals - Occurs as well-formed crystals showing good external form.
Habit:
Massive - Granular - Common texture observed in granite and other igneous rock.
Hardness:
6.5-7.5
Luminescence:
Fluorescent, Short UV=pink, Long UV=orange.
Luster:
Vitreous - Resinous
Streak:
brownish white
Optical Properties of Grossular
Gladstone-Dale:
CI meas= 0.003 (Superior) - where the CI = (1-KPDmeas/KC) CI calc= 0.009 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2067,KPDmeas= 0.2078,KC= 0.2085 Ncalc = 1.71 - 1.78
Optical Data:
Isotropic, n=1.734-1.75.
Calculated Properties of Grossular
Electron Density:
Bulk Density (Electron Density)=3.55 gm/cc note: Specific Gravity of Grossular =3.57 gm/cc.
Fermion Index:
Fermion Index = 0.0093002212 Boson Index = 0.9906997788
Photoelectric:
PEGrossular = 4.35 barns/electron U=PEGrossular x rElectron Density= 15.44 barns/cc.
Radioactivity:
GRapi = 0 (Gamma Ray American Petroleum Institute Units) Grossular is Not Radioactive
Grossular Classification
Dana Class:
51.04.03b.02(51)Nesosilicate Insular SiO4 Groups Only
Chemical Formula: 
