In xenoliths in leucite tephrite lava. Milarite group; structure determined.
IMA Status:
Approved IMA 2004 (Dana # Added)
Locality:
A quarry at the Bellerberg volcano lava field, near Ettringen, 2 km north of Mayen, Laacher See region, eastern Eifel area, Germany. Link to MinDat.org Location Data.
Name Origin:
After the authors’ hosting and supporting institution, "Universität Wien", and is derived from the university’s proper name "ALma MAter RUDolphina".
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Mihajlovic T , Lengauer C L , Ntaflos T , Lolitsch U , Tillmanns E , Neues Jahrbuch fur Mineralogie, Abhandlungen , 179 (2004) p.265-294, Two new minerals, rondorfite, Ca8Mg[SiO4]4Cl2, and almarudite,, K(box,Na)2(Mn,Fe,Mg)2(Be,Al)3[Si12O30], and a study of iron-rich wadalite,, Ca12[(Al8Si4Fe2)O32]C16, from the Bellerberg (Bellberg) volcano, Eifel, Germany, Locality: Bellerberg volcano lava field, 2 km N of Mayen,, Eastern Eifel volcanic area, Eifel, Germany
Physical Properties of Almarudite
Cleavage:
None
Color:
Yellow, Orange.
Diaphaneity:
Transparent
Fracture:
Brittle - Irregular - Very brittle fracture producing irregular fragments
Habit:
Euhedral Crystals - Occurs as well-formed crystals showing good external form.
Habit:
Tabular - Form dimensions are thin in one direction.
Luster:
Vitreous (Glassy)
Streak:
light orange
Optical Properties of Almarudite
Gladstone-Dale:
CI calc= 0.006 (Superior) - where the CI = (1-KPDcalc/KC) KPDcalc= 0.2057,KC= 0.207 Ncalc = 1.56
Optical Data:
Uniaxial (-), e=1.559, w=1.56, bire=0.0010.
Calculated Properties of Almarudite
Electron Density:
Bulk Density (Electron Density)=2.69 gm/cc note: Specific Gravity of Almarudite =2.72 gm/cc.
Fermion Index:
Fermion Index = 0.03 Boson Index = 0.97
Photoelectric:
PEAlmarudite = 4.29 barns/electron U=PEAlmarudite x relectron= 11.53 barns/cc.
Radioactivity:
GRapi = 47.90 (Gamma Ray American Petroleum Institute Units)
Concentration of Almarudite per GRapi unit = 2.09 (%)
Estimated Radioactivity from Almarudite - barely detectable