Burbankite

Chemical formula: (Na,Ca)₃(Sr,Ba,Ce³⁺)₃(CO₃)₅

Burbankite is a rare carbonate of sodium, calcium, and rare earth elements, forming prismatic crystals with a vitreous luster, prized by collectors.

## Characteristics Burbankite is a complex carbonate of sodium, calcium, strontium, and rare earth elements. It forms hexagonal, prismatic crystals, often terminated by flat faces. Crystals are frequently longitudinally striated and can reach several centimeters in length. It typically occurs as embedded, well-formed crystals or in granular aggregates. It is a brittle mineral. ## Physical Properties This mineral is characterized by a hardness of 3.5-4 on the Mohs scale and a density of approximately 3.5 g/cm³. The luster is vitreous to resinous on fresh surfaces, and may be somewhat greasy on crystal faces. It is transparent to translucent. Some specimens may exhibit weak, orange fluorescence under ultraviolet light. ## Colors and Varieties Burbankite most commonly ranges in color from pale yellow, through yellowish-green, grayish-green, to pinkish and gray. It can sometimes be colorless. Color variability results from differences in chemical composition, especially the proportions of rare earth elements. No named varieties of this mineral are distinguished. ## History and Name The mineral's name honors Wilbur Swett Burbank (1898-1975), a geologist with the United States Geological Survey, who studied the San Juan Mountains region in Colorado. Burbankite was first described in 1953 based on specimens found in carbonatite veins in the Bearpaw Mountains, Montana, USA. ## Uses Burbankite has no industrial applications. Due to its rarity, attractive crystals, and interesting chemical composition, it is a prized collector's mineral.

Properties

Mohs hardness: 3.5-4
Color: Colorless, grayish yellow, pale yellow, pink, pale greenish, reddish brown.
Luster: Vitreous, Resinous
Streak: White
Density: 3.50
Cleavage: <mi>{10_10}</mi>
Fracture: Conchoidal to subconchoidal
Transparency: Transparent,Translucent
Crystal system: Hexagonal

Diagnostic features

## Identification Burbankite can be identified by its characteristic, hexagonal, prismatic crystals, often with longitudinal striations. Vitreous luster, relatively low hardness (about 3.5-4), and reaction with acids (effervescence) are key diagnostic features. Occurrence in specific geological environments, such as carbonatites, is also an important clue. ## Distinguishing from Similar Minerals Burbankite is sometimes confused with other carbonates or minerals of similar habit, such as apatite or some zeolites (e.g., natrolite). It is distinguished from apatite by its lower hardness (apatite has a hardness of 5) and stronger reaction with acids. Unlike many zeolites, burbankite has a higher density and does not occur in gas vesicles in volcanic rocks, but rather in carbonatites and alkaline rocks. ## Crystal Forms Burbankite crystals have a prismatic or columnar habit, with a hexagonal outline. They are usually terminated by flat pinacoids. They often occur as embedded, single crystals or in radial and granular aggregates.

Geological environment

## Genesis Burbankite is a hydrothermal mineral, crystallizing in the late stages of the formation of carbonatites and alkaline rock complexes, such as nepheline syenites. It forms in veins and mineral pockets where sodium, strontium, and rare earth elements are concentrated. ## Mineral Associations This mineral often co-occurs with other rare carbonatite and alkaline minerals. Its typical associations include: calcite, ankerite, barite, fluorite, as well as rarer minerals like ancylite, remondite, nahcolite, and pirssonite. ## Localities The most important and classic burbankite localities in the world are the Bearpaw Mountains in Montana (USA), where it was discovered. Significant specimens also come from the alkaline complex on the Kola Peninsula in Russia (Khibiny and Lovozero massifs) and from the Mont Saint-Hilaire complex in Quebec (Canada). Other known localities include the Ilimaussaq complex in Greenland and carbonatites in Jacupiranga, Brazil.

Rarity

Rare

For collectors

## Quality Criteria Most prized by collectors are well-formed, sharply terminated, single crystals with high transparency and an intense yellow or yellowish-green color. Specimens where burbankite crystals are aesthetically set on a contrasting rock matrix, for example, in association with other rare minerals, are also highly valued. Crystal size is important – specimens exceeding 2-3 cm are already a rarity. ## Popular Localities The most famous collector specimens, known for their sharp forms and good color, come from localities in Montana (USA) and Mont Saint-Hilaire in Canada. Russian specimens from the Kola Peninsula, although often large, may be less ideally formed, but are also sought after due to their scientific significance and rich mineral associations.

Care and storage

## Cleaning Burbankite specimens should be cleaned very carefully, using a soft brush to remove dust. If necessary, distilled water can be used, but prolonged soaking should be avoided. After wet cleaning, the specimen should be thoroughly dried. ## What to Avoid Burbankite is a carbonate, therefore it reacts with acids, even weak ones, leading to its damage or complete dissolution. Contact with any chemicals should be avoided. It is a brittle mineral, sensitive to impact and scratching. It should not be heated or exposed to sudden temperature changes. ## Storage Burbankite specimens are best stored in separate, padded boxes or display cases to avoid contact with harder minerals. They should be protected from dust, humidity, and direct sunlight, which can cause some specimens to fade over time.

External references

https://www.mindat.org/min-803.html