Pitticite

An amorphous Fe3+ hydrous arsenate sulphate of questionable validity. Chemical composition appears to be variable. "Microprobe analyses of 7 pitticites from various localities indicate that it is a gel-like mineral of widely varying composition with no apparent stoichiometry. Previously reported minor amounts of Si, Ca, P and Al are constituents of pitticites but are non-essential. Pitticite is retained as a generic name for amorphous, gel-like, ferric iron arsenate minerals of varying chemical composition" (Dunn, 1982). A secondary mineral formed at near-surface conditions from the oxidation of arsenopyrite, realgar, or orpiment; also forms as a recent deposit from mine and spring waters.

History

Activities related to discovery and approval of the group members

Structural context

Pitticite
Crystal System amorphous
a
b
c
alpha
beta
gamma
volume

Based on 1 measurements

Chemical context

Stoichiometric formulas

Pitticite
mindat.org
  • March 13, 2023(Fe, AsO4, H2O) (?)Minor, non-essential S, Si, Ca, P and Al may be present.
IMA
  • March 13, 2023[Fe,AsO4,SO4,H2O] (?)
mineralogy.rocks
  • Aug. 30, 2022(Fe,SO4,AsO4,H2O)

Elements recorded on EPMA

1
Al
1
As
1
Co
1
Cu
1
Fe
1
H
1
K
1
Ni
1
O
1
Zn

Physical properties

ColorColor entities, recognized using a custom trained NER model
  • yellowish
  • pale yellowish
  • reddish-brown
  • reddish brown
  • brownish red
  • brownish black
      Color noteOriginal color note from the source
      Yellowish, reddish-brown, brownish red to brownish black, grey, nearly white; pale yellowish to reddish brown in transmitted light.
      StreakStreak entities, recognized using a custom trained NER model
          Streak noteOriginal streak note from the source
          Yellow to white
          Lustre
          Vitreous
          Greasy
          Dull
          Fracture
          Irregular/Uneven
          Splintery
          Conchoidal
          Transparency
          Transparent
          Opaque
          Tenacity
          very brittle
          Hardness
          2—3
          Measured density
          2.2—2.5