Hollandite

In 2012, the IMA revised the nomenclature of the Hollandite Supergroup (Biagioni et al., 2013). Hollandite is now redefined as the (more widespread) Ba-Mn3+ end-member of the coronadite group; concurrently, type hollandite is redefined as ferrihollandite, a new name to denote the Ba-Fe3+ end-member (Biagioni et al., 2013). The original type locality for hollandite is now that of ferrihollandite; the neotype locality for hollandite is Gowari Wadhona (misspelt Gowani Wadhona in Biagioni et al., 2013). Visually indistinguishable from cryptomelane and several other manganese oxide minerals. Chemically similar to romanèchite.

History

Activities related to discovery and approval of the group members

Structural context

Hollandite
Crystal System monoclinicSpace Group C2/m
a6.94—10.227 (9.9444)
b2.7846—14.907 (8.1867)
c2.866—10.191 (6.0236)
alpha90
beta90—92.27 (90.4374)
gamma90
volume275.014—1518.9 (424.6402)

Based on 19 measurements

Chemical context

Stoichiometric formulas

Hollandite
mindat.org
  • March 13, 2023Ba(Mn4+6Mn3+2)O16Formerly defined as Ba(Mn4+,Mn2+)8O16.
IMA
  • March 13, 2023Ba(Mn4+6Mn3+2)O16
mineralogy.rocks
  • Aug. 30, 2022Ba(Mn4+6Mn3+2)O16

Elements recorded on EPMA

18
O
13
Ti
12
Mg
8
Ba
7
Mn
6
K
6
Rb
4
Fe
2
Al
2
Pb
1
Li
1
Na
1
Sr

Physical properties

ColorColor entities, recognized using a custom trained NER model
  • silvery-grey
  • greyish black
Color noteOriginal color note from the source
Silvery-grey to greyish black, black
StreakStreak entities, recognized using a custom trained NER model
    Streak noteOriginal streak note from the source
    Black
    Lustre
    Metallic
    Transparency
    Opaque
    Tenacity
    brittle
    Hardness
    4—6
    Calculated density
    4.93