Peprossiite-(Ce)

The first anhydrous rare-earth-element borate. Formed in cavities in sanidine ejecta by circulation of pneumatolytic to hydrothermal fluids, probably above 350 °C. Peprossiite-(Ce) was first found by Italian mineral collector Giorgio Penco in 1986.

History

Activities related to discovery and approval of the group members

Structural context

Peprossiite-(Ce)
Crystal System hexagonalCrystal Class ditrigonal dipyramidalSpace Group P-62m
a4.596—4.654 (4.6207)
b4.596—4.654 (4.6207)
c9.309—9.414 (9.3657)
alpha90
beta90
gamma120
volume170.292—176.587 (173.1853)

Based on 3 measurements

Chemical context

Stoichiometric formulas

Peprossiite-(Ce)
mindat.org
  • Dec. 10, 2024CeAl2(B3.67Si0.33)O10.67
  • March 13, 2023(Ce,La)(Al3O)2/3B4O10
IMA
  • March 13, 2023(Ce,La)(Al3O)2/3B4O10
mineralogy.rocks
  • Aug. 30, 2022(Ce3+,La)Al2B4O10.67

Elements recorded on EPMA

2
Al
2
B
2
O
1
Ca
1
La
1
Pr
1
Si
1
Th

Physical properties

ColorColor entities, recognized using a custom trained NER model
  • light yellow
  • colourless
Color noteOriginal color note from the source
Light yellow; colourless in transmitted light
StreakStreak entities, recognized using a custom trained NER model
    Streak noteOriginal streak note from the source
    White
    Lustre
    Vitreous
    Transparency
    Transparent
    Translucent
    Hardness
    2
    Calculated density
    3.476