Piergorite-(Ce)

Chemical formula: Ca₈Ce³⁺₂AlLiSi₆B₈O₃₆(OH)₂

Piergorite-(Ce) is a very rare mineral from the datolite group, discovered in Italy, forming colorless to pale pink, tabular crystals.

## Characteristics Piergorite-(Ce) is an extremely rare borosilicate belonging to the datolite group. It was approved as a new mineral species by the IMA in 2019. It occurs as very fine, tabular crystals, usually not exceeding 0.2 mm, which form rosette-like or radial aggregates. The crystals are colorless to pale pink and exhibit a vitreous luster. ## Physical Properties This mineral is characterized by a hardness of approximately 5 on the Mohs scale. It is transparent to translucent, with a white streak. Its crystals are brittle and exhibit an uneven fracture. Due to the small size of the crystals, many physical properties are difficult to measure precisely. ## History and Name The name "Piergorite-(Ce)" was given in honor of Pier and Andrea Gori, two Italian mineral collectors who found the first samples of this mineral. The suffix "-(Ce)" refers to the dominant rare earth element in its chemical composition - cerium. The mineral was described by a research team led by Ferdinando Bellatreccia based on samples from Tre Croci, Italy.

Properties

Mohs hardness
5
Color
Colorless to pale yellow
Luster
Vitreous
Streak
White
Density
0
Cleavage
{010}
Fracture
Uneven
Transparency
Translucent
Crystal system
Monoclinic

Diagnostic features

## Identification Identification of Piergorite-(Ce) is impossible without advanced analytical techniques, such as Raman spectroscopy or chemical analysis using an electron microprobe (EDS/WDS). In collector conditions, identification relies on a label from a trusted source and precise locality information. ## Distinguishing from similar minerals It can be confused with other rare borosilicates from the same locality, such as datolite, gadolinite-(Ce), or hellandite-(Ce). Visual distinction is practically impossible and requires specialized analysis. ## Crystal forms It forms thin, tabular crystals with a hexagonal outline, which combine into small, rosette-like or radial aggregates.

Geological environment

## Genesis Piergorite-(Ce) forms as a result of hydrothermal processes within sanidinite volcanic blocks. It crystallizes in small cavities (geodes) within these rocks, under conditions of low pressure and high temperature. ## Mineral associations This mineral co-occurs with other minerals typical of this environment, such as sanidine, tridymite, hematite, as well as rarer ones like vicanite-(Ce) or fluorite. ## Localities The only confirmed occurrence of Piergorite-(Ce) in the world is its type locality: Tre Croci, near Vetralla, in the province of Viterbo, Italy.

Rarity

Extremely rare

For collectors

## Quality criteria As a "micromount" type mineral, the value of a specimen is primarily determined by the quality and size of the crystals in the aggregate, their transparency, and their aesthetic placement on the rock matrix. The most desirable are well-formed, radial aggregates with clearly visible individual crystals. ## Popular localities The only source of specimens is the type locality in Tre Croci, Italy. Material from this location is extremely limited and sought after by specialized collectors of rare minerals and micromounts.

Care and storage

## Cleaning Due to its extreme rarity and fragility, mechanical cleaning is not recommended. If absolutely necessary, compressed air (from a safe distance) can be used to remove loose dust. Avoid contact with water and chemicals. ## What to avoid Avoid all ultrasonic cleaners, acids, solvents, and sudden temperature changes. The mineral is brittle, so protect it from impacts and vibrations. ## Storage Specimens should be stored exclusively in stable, sealed "micromount" containers, away from light, dust, and moisture. It is best to store them under stable room conditions.

External references

Sources

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