Fingerite - Occurrence, Properties, and Distribution

Fingerite is a triclinic-pinacoidal black mineral containing vanadium, oxygen and copper. It was first discovered in 1985 from Izalco volcano, El Salvador. The mineral was named after Larry W. Finger, American mineralogist, Carnegie Institution, Washington, D.C., USA.

Properties of Fingerite

The following are the key properties of Fingerite:

• Cell Data
  • Space Group: P1
  • a = 8.1576(6)
  • b = 8.2691(5)
  • c = 8.0437(7)
  • α = 107.144(5)°
  • β = 91.389(7)°
  • γ = 106.441(5)°
  • Z = 1.
• Crystal Data
  • Triclinic
  • Point Group: 1
  • As crystals, to 150 µm, may be subhedral or anhedral; equant or plate-like
  • Twinning: As contact and multiple twins, by rotation about [010]
  • X-ray Powder Pattern: 6.48 (100), 3.042 (80), 2.822 (70), 2.025 (70), 3.894 (60), 3.617 (60), 3.293 (60d).
• Chemical Composition

  Elements	Content 1	Content 2	Content 3
  CuO	59.3	59.53	61.59
  V2O5	39.65	39.67	38.41
  Total	98.95	99.20	100

• Optical Properties
  • Optical Class: Biaxial.
• Estimated Properties

  Electron density	Bulk density (electron density) = 4.48 g/cm3 note: Specific gravity of Fingerite = 4.78 g/cm3
  Photoelectric	PEFingerite = 26.34 barns/electron U = PEFingerite x ρElectron density = 117.86 barns/cm3
  Fermion index	Fermion index = 0.0006 Boson index = 0.9993
  Radioactivity	Fingerite is not radioactive.

How to Identify Fingerite

Fingerite is an opaque black mineral having a dark red brown streak and metallic luster.

Global Distribution

Fingerite is widely found in the Izalco volcano, El Salvador.

Occurrence of Fingerite and Useful Mineral Association

Fingerite occurs as a rare component of vanadium-bearing sublimates in fumaroles on a basaltic volcanic cone, formed between 100 and 200°C.

References

• Fingerite – Mindat
• Fingerite Mineral Data – Webmineral
• Fingerite.pdf - Rruff Project Website - University of Arizona