Formed by repeated natural leaching of nitrate ore with reprecipitation in irregular pods above the local regolith.
IMA Status:
Approved IMA 1970
Locality:
Oficina Alemania and ten km west of Oficina Mar�ia Elena; an ore in the Taltal nitrate district, Antofagasta; locally abundant in near-surface nitrate layers throughout the Atacama Des
Link to MinDat.org Location Data.
Name Origin:
Named for James Thomas Humberstone (1850-1939), industrial chemist whose contributions permit economical extraction of nitrate from the Chilean deposits.
Brittle - Uneven - Very brittle fracture producing uneven fragments.
Hardness:
2.5 - Finger Nail
Luster:
Vitreous (Glassy)
Streak:
white
Optical Properties of Humberstonite
Gladstone-Dale:
CI meas= 0.015 (Superior) - where the CI = (1-KPDmeas/KC) CI calc= 0.014 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2022,KPDmeas= 0.202,KC= 0.2052 Ncalc = 1.46
Optical Data:
Uniaxial (-), e=1.436, w=1.474, bire=0.0380.
Calculated Properties of Humberstonite
Electron Density:
Bulk Density (Electron Density)=2.25 gm/cc note: Specific Gravity of Humberstonite =2.25 gm/cc.
Fermion Index:
Fermion Index = 0.03 Boson Index = 0.97
Photoelectric:
PEHumberstonite = 2.42 barns/electron U=PEHumberstonite x relectron= 5.46 barns/cc.
Radioactivity:
GRapi = 149.14 (Gamma Ray American Petroleum Institute Units)
Concentration of Humberstonite per GRapi unit = 0.67 (%)
Estimated Radioactivity from Humberstonite - barely detectable