Eucryptite

Today, in this article, we are going to talk about Eucryptite. Eucryptite is a topic that has sparked the interest and curiosity of many people over the years. Whether for its relevance in today's society, its impact on history, its potential for the future, or simply for its emotional value, Eucryptite is a topic that deserves to be analyzed and discussed. Throughout this article, we will explore different aspects of Eucryptite, from its origin and evolution to its influence on various areas of life. We hope this reading is informative and enriching for all those seeking a greater understanding of Eucryptite.

Eucryptite
Eucryptite grains in albite from the type locality (size: 9.3 × 7.0 × 2.8 cm)
General
CategorySilicate mineral
FormulaLiAlSiO4
IMA symbolEcp[1]
Crystal systemTrigonal
Crystal classRhombohedral (3)
H-M symbol: (3)
Space groupR3
Unit cella = 13.48, c = 9.01 ; Z = 18
Identification
ColorBrown, colorless, white
Crystal habitRare as euhedral crystals, coarse crystalline aggregates and massive
CleavageIndistinct on {1010} and {0001}
FractureConchoidal
TenacityVery brittle
Mohs scale hardness6.5
LusterVitreous
StreakWhite
DiaphaneityTransparent to translucent
Density2.67
Optical propertiesUniaxial (+)
Refractive indexnω = 1.570 – 1.573 nε = 1.583 – 1.587
Birefringenceδ = 0.013
Other characteristicsFluoresces pink to red or orange under SW UV
References[2][3][4]

Eucryptite is a lithium bearing aluminium silicate mineral with formula LiAlSiO4. It crystallizes in the trigonal – rhombohedral crystal system. It typically occurs as granular to massive in form and may pseudomorphically replace spodumene. It has a brittle to conchoidal fracture and indistinct cleavage. It is transparent to translucent and varies from colorless to white to brown. It has a Mohs hardness of 6.5 and a specific gravity of 2.67. Optically it is uniaxial positive with refractive index values of nω = 1.570 – 1.573 and nε = 1.583 – 1.587.

Its typical occurrence is in lithium-rich pegmatites in association with albite, spodumene, petalite, amblygonite, lepidolite and quartz.[3]

It occurs as a secondary alteration product of spodumene. It was first described in 1880 for an occurrence at its type locality, Branchville, Connecticut.[2] Its name was from the Greek for well concealed, for its typical occurrence embedded in albite.[2][3]

References

  1. ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. ^ a b c Mindat.org
  3. ^ a b c Handbook of Mineralogy
  4. ^ Webmineral data


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