Krausite - Occurrence, Properties, and Distribution

Topics Covered

Introduction to Krausite
Properties of Krausite
How to Identify Krausite
Global Distribution
Occurrence of Krausite and Useful Mineral Association

Introduction to Krausite

Molecular Formula – KFe(SO4)2H2O

Krausite comprises potassium, iron, sulphates and water and was named after Dr. Edward Henry Kraus (1875-1973), American mineralogist from the University of Michigan.

Properties of Krausite

The following are the key properties of Krausite:

Cell Data

  • Space Group: P21/m
  • a = 7.908 – 7.920
  • b = 5.152 – 5.146
  • c = 8.988 – 9.014
  • Z = 2

Crystal Data

  • Monoclinic
  • Point Group: 2/m
  • Crystals are equant, may be tabular or short prismatic, larger crystals, to 5 mm, are typically rough; forms massive crusts.
  • X-ray powder pattern: 3.09 (100), 4.40 (74), 6.59 (66), 3.69 (64), 4.26 (45), 2.768 (40), 2.579 (38)

Chemical Composition

Elements Content 1 Content 2 Content 3
SO3 51.05 53.02 52.59
SiO2 2.19    
Fe2O3 24.94 25.9 26.17
FeO 0.24    
CaO 0.12
Na2O 0.64    
K2O 14.71 15.28 15.44
H2O 5.59 5.8 5.9
insol 0.92    
Total 100.00 101.2 100.00

Optical Properties'

  • Optical Class: Biaxial (+)
  • α = 1.588 β = 1.650 γ = 1.722

Estimated Properties

Electron density Bulk density (electron density)=2.81 g/cm3
note: Specific gravity of Helvine =2.84 g/cm3
Photoelectric PEKrausite = 7.96 barns/electron
U=PEKrausite x ?electron= 22.39 barns/cc.
Fermion index Fermion Index = 0.0057001889
Boson Index = 0.9942998111
Radioactivity Krausite is not radioactive

How to Identify Krausite

Krausite is transparent to opaque and has a pale lemon-yellow, yellowish green, gray color. It is pale yellow in color to colorless in transmitted light. It has white streaks and a vitreous to dull luster.

Global Distribution

Krausite is distributed in the USA, in the Sulfur Hole prospect, near Borate, about 10 km northeast

of Yermo, Calico Hills, San Bernardino Co., California, and in the Coral Reefs district, Wayne

Co., Utah, USA. It is also distributed at the Santa Maria mine, Velarde˜na, Durango, Mexico and in the Santa B´arbara sulfur mine, El Palmar district, Jujuy Province, Argentina and it is also found in Campi Flegrei, near Naples, Campania, Italy.

Occurrence of Krausite and Useful Mineral Association

Krausite is an uncommon secondary mineral in sulfate-bearing cherts and also formed on a dump by post-mine oxidation of pyrite. It is associated with alunite, coquimbite, romerite, voltaite, metavoltine copiapite, voltaite and halotrichite.


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