Editorial Feature

Schirmerite – Occurrence, Properties and Distribution

Schirmerite was discovered in 1977, in the Colorado District of the USA. It is named after Dr.J.H.L Schirmer, former superintendent of the U.S.Mint. It is also known by the name beegerite.

Properties of Schirmerite

The key physical properties of Schirmerite are as below:

  • Cell Data
    • Space group: Bbmm,Bbm2 or Bb21m
    • a = 13.44
    • c=4.022
    • Z = 8
  • Crystal Data
    • Orthorhombic
    • Point group: mm2
    • Crystals – as lath-shaped grains, to several mm.;also massive and fine-granular.
    • X-ray powder pattern: 2.035 (100), 3.207 (90), 2.923 (90), 2.878 (70), 2.873 (70), 2.786 (70), 2.382 (70)
  • Chemical Composition
    Elements Content 1 Content 2 Content 3
    Ag 9.1 9.51 8.97
    Cu 0.1 - -
    Pb 29.0 18.27 34.47
    Bi 45.9 55.26 40.56
    S 16.71 16.96 16.00
  • Optical Properties
    • Anisotropism – Weak in air, distinct to strong in oil, in gray to black
    • R1–R2 : (400) 42.6–46.6, (420) 43.0–47.3, (440) 43.4–48.0, (460) 43.6–48.2, (480) 43.5–48.2, (500) 43.2–48.0, (520) 42.9–47.7, (540) 42.4– 47.2, (560) 42.0–46.7, (580) 41.7–46.2, (600) 41.4–46.0, (620) 41.2–45.7, (640) 41.1–45.6, (660) 41.0–45.5, (680) 40.9–45.3, (700) 40.9–45.1
  • Estimated Properties
    Electron density Bulk density (electron density)= 6.95 g/cm3
    note: Specific gravity of Schirmerite = 8.26 g/cm3
    Photoelectric PESchirmerite = 1,347.60 barns/electron
    U=PESchirmerite x ρelectron density= 9,366.52 barns/cm3
    Fermion index Fermion index = 0.04
    Boson index = 0.96
    Radioactivity
     
    GRapi = 0 (Gamma Ray American Petroleum Institute Units)
    Schirmerite is not radioactive

How to Identify Schirmerite

Schirmerite appears as a gray, lead gray or iron black textures present in granite and igneous rocks. It is an opaque, brittle, massive, granular structure having a metallic luster. It is a non magnetic and non-fluorescent mineral. The density of this mineral is 6.74 g/cm3 and hardness is 2, close to gypsum.

Global Distribution

Schirmerite is widely distributed in the following locations:

  • USA- from Treasure Vault, Geneva District, Clear Creek, Lake District, Hinsdale and California
  • Scotland – Corrie Buie, Perthshire
  • Romania – from Toroiga mine and Baia Borsa
  • China – from Shanhu W-Sn deposit, Guangxi Zhuangzu Autonomous Region.

Occurrence of Schirmerite and Useful Mineral Association

Schirmerite occurs in the disseminated through quartz. Schirmerite is commonly associated with ores such as galena, matildite, lillianate, bismuthinite, aikinite, hessite and clausthalite.

References

Tell Us What You Think

Do you have a review, update or anything you would like to add to this article?

Leave your feedback
Your comment type
Submit