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Light yellow; colourless ...
After Giuseppe "Pep" Rossi (1938-1990), Italian mineralogist and crystallographer.
The first anhydrous rare-earth-element borate.

Classification of Peprossiite-(Ce)

Approved 1999

C : Triborates
A : Neso-triborates

3 : AmBn[XO3]p URL:
Please feel free to link to this page.

Type Occurrence of Peprossiite-(Ce)

General Appearance of Type Material:
Light yellow flakes in vugs among sanidine crystals.
Place of Conservation of Type Material:
Museo di Mineralogia, University of Rome, Rome, Italy. and: Museum National d'Histoire Nazturelle, paris, France.
Year of Discovery:
Geological Setting of Type Material:
Sanidine volcanic ejectum within pyroclastics.
Associated Minerals at Type Locality:

Physical Properties of Peprossiite-(Ce)

Diaphaneity (Transparency):
Transparent, Translucent
Light yellow; colourless in transmitted light
Hardness (Mohs):
On {0001}, perfect; on {110} ({110} ?), distinct.
3.45 g/cm3 (Measured)    3.476 g/cm3 (Calculated)

Crystallography of Peprossiite-(Ce)

Crystal System:
Class (H-M):
6 m2 - Ditrigonal Dipyramidal
Space Group:
Cell Parameters:
a = 4.61(1) Å, c = 9.358(7) Å
a:c = 1 : 2.03
Unit Cell Volume:
V 172.23 ų (Calculated from Unit Cell)
Small flakes with a hexagonal outline.

Optical Data of Peprossiite-(Ce)

Uniaxial (+)
RI values:
nω = 1.703 nε = 1.711
Max Birefringence:
δ = 0.008
Image shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:

Chemical Properties of Peprossiite-(Ce)

All elements listed in formula:

Relationship of Peprossiite-(Ce) to other Species

6.CA.15InderiteMgB3O3(OH)5 · 5H2O
6.CA.20KurnakoviteMgB3O3(OH)5 · 5H2O
6.CA.25InderboriteCaMg(H3B3O7)2 · 8H2O
6.CA.30MeyerhofferiteCa2(H3B3O7)2 · 4H2O
6.CA.35InyoiteCa(H4B3O7)(OH) · 4H2O
6.CA.55OlshanskyiteCa2[B3O3(OH)6](OH) · 3H2O

Other Names for Peprossiite-(Ce)

Name in Other Languages:

Other Information

Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for Peprossiite-(Ce)

Reference List:
Della Ventura, G., Parodi, G.C., Mottana, A., and haussidon, M. (1993) Peprossiite-(Ce), a new mineral from Campagnano (Italy): the first anhydrous rare-earth-element borate. European Journal of Mineralogy: 5: 53-58.

Jambor, John L., and Jacek Puziewicz (1993) New Mineral Names. American Mineralogist: 78: 1109.

Grew, E.S., and Anovitz, L.M. (1996) BORON: Mineralogy, Petrology and Geochemistry, second edition, as revised (2002).

New Minerals (1997), New Minerals 1990-1994.

Callegari, A., Caucia, F., Mazzi, F., Oberti, R., Ottolini, L., and Ungaretti, L. (2000) The crystal structure of peprossiite-(Ce), an anhydrous REE and Al mica-like borate with square-pyramidal coordination for Al. American Mineralogist: 85: 586-592.

Internet Links for Peprossiite-(Ce)

Localities for Peprossiite-(Ce)

map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
(TL) indicates type locality for a valid mineral species. (FRL) indicates first recorded locality for everything else. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.
  • Latium
    • Rome Province
      • Sacrofano Caldera
        • Campagnano di Roma
Della Ventura, G., Parodi, G.C., Mottana, A., and Chaussidon, M. (1993) Peprossiite-(Ce), a new mineral from Campagnano (Italy): the first anhydrous rare-earth-element borate. European Journal of Mineralogy: 5: 53-58.
    • Viterbo Province
      • Vico Lake
Della Ventura, G., Bellatreccia, F., Caprilli, E., Rossi, P., Tamagnini, F., Fiori, S., 2004. Dieci anni di micromineralogia laziale. Il Cercapietre. Not. del Gruppo Mineralogico Romano, 1-2
No reference listed
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