Bridgesite-(Ce)

Chemical formula: CaCe<sup>3+</sup><sub>2</sub>Cu<sup>2+</sup><sub>6</sub>(S<sup>6+</sup>O<sub>4</sub>)<sub>4</sub>(OH)<sub>12</sub>·8H<sub>2</sub>O

Bridgesite-(Ce) is a very rare, secondary sulfate of copper, calcium, and cerium, forming blue, tabular crystals.

## Characteristics Bridgesite-(Ce) is a hydrated hydroxyl sulfate of calcium, cerium, and copper. This mineral forms very small, thin, tabular crystals with a hexagonal outline, usually not exceeding 0.2 mm. These crystals often occur as rosetted or spherical aggregates. Due to its chemical composition and formation conditions, it is associated with the weathering processes of other copper minerals. ## Physical Properties Bridgesite-(Ce) crystals are very brittle. The Mohs hardness is low, at 2. The luster is vitreous to pearly on cleavage surfaces. The mineral is transparent to translucent. ## Colors and Varieties Bridgesite-(Ce) has a characteristic, light blue color. The streak is also light blue. No varieties of this mineral have been distinguished. ## History and Name The mineral was named in honor of Stuart J. Bridges (born 1940), an Australian mineral collector and dealer who provided the first samples for study. The suffix "(Ce)" in the name indicates the dominant rare earth element in its structure, which is cerium. It was approved as a new mineral species by the International Mineralogical Association (IMA) in 2010 (IMA2010-037).

Properties

Mohs hardness
2
Luster
Vitreous
Streak
Light blue
Density
3.25
Cleavage
Perfect on {0001}
Fracture
Brittle
Transparency
Transparent to translucent
Crystal system
Trigonal

Diagnostic features

## Identification The mineral can be identified by its characteristic light blue color, hexagonal outline of thin, tabular crystals, and occurrence as small, rosetted aggregates. Its secondary origin in the oxidation zones of copper deposits is also key. ## Distinguishing from Similar Minerals It may be confused with other blue secondary copper minerals, such as chalcanthite, linarite, or brochantite. Differentiation requires analysis of crystal form (thin, hexagonal tablets) and often advanced research methods, such as XRD or EDS, due to the small size of the specimens. ## Crystal Forms Bridgesite-(Ce) forms thin, tabular crystals with a hexagonal outline. These crystals combine into rosetted or spherical aggregates.

Geological environment

## Genesis This is a secondary mineral, formed in the oxidation (weathering) zones of copper ore deposits. It forms as a result of the reaction of acidic, sulfate-rich waters with primary minerals in the presence of rare earth elements. ## Mineral Associations It co-occurs with other secondary minerals such as brochantite, gypsum, jarosite, chalcanthite, chalcopyrite, pyrite, and quartz. ## Localities The only known locality (type locality) is the Mount Gordon Copper Mine, located approximately 120 km north of Mount Isa in Queensland, Australia.

Rarity

Extremely rare

For collectors

## Quality Criteria The most prized specimens are those with well-formed, sharp crystals forming aesthetic, rosetted aggregates on a contrasting rock matrix. The size of the crystals and aggregates is a key factor, although even the largest specimens are microscopic. The intensity and purity of the blue color also affect the value. ## Popular Localities The only source of bridgesite-(Ce) specimens is the Mount Gordon mine in Australia, which makes every specimen from this locality highly sought after by collectors specializing in rare minerals or minerals from specific localities (so-called "locality collecting").

Care and storage

## Cleaning Specimens should only be cleaned with compressed air to remove dust. Due to the extreme delicacy and small size of the crystals, any mechanical contact, including with water or a brush, is highly risky and may damage the specimen. ## What to Avoid Avoid contact with water, chemicals, ultrasound, and sudden temperature changes. The crystals are very brittle and sensitive to mechanical shocks. ## Storage Bridgesite-(Ce) specimens should be stored in stable conditions, in sealed "micromount" boxes, to protect them from dust, mechanical damage, and humidity changes.

Sources

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