Editorial Feature

Schirmerite – Occurrence, Properties and Distribution

May 8 2013

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	PE_Schirmerite = 1,347.60 barns/electron U=PE_Schirmerite 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.