Bobtraillite

Chemical formula: (Na,&#₉₇₄₄;)₁₂(&#₉₇₄₄;,Na)₁₂Sr₁₂Zr₄+₁₄(Si₃O₉)₁₀[Si₂BO₇(OH)₂]₆·₁₂H₂O

Bobtraillite is an extremely rare mineral from the eudialyte group, discovered in Canada, with a complex chemical composition containing zirconium, strontium, and boron.

## Characteristics Bobtraillite is a mineral with an exceptionally complex chemical structure, belonging to the eudialyte group. It occurs as very fine, hexagonal crystals, rarely exceeding 1 mm in size. It typically forms granular aggregates or appears as single, dispersed grains within the host rock. Its crystals have the form of short, six-sided prisms. It is a transparent to translucent mineral with a vitreous luster. ## Physical Properties Bobtraillite is characterized by a Mohs hardness of approximately 5. It has a white streak and a vitreous luster. The mineral's density has been calculated at 3.03 g/cm³. It does not exhibit cleavage, and its fracture is uneven. ## Colors and Varieties This mineral is colorless or pale yellow to yellow. Due to its rarity and small crystal size, no distinct color varieties or commercial forms are recognized. ## History and Name Bobtraillite was discovered at the Poudrette quarry, Mont Saint-Hilaire in Quebec, Canada. It was described and approved as a new mineral species by the International Mineralogical Association (IMA) in 2009. Its name honors Dr. Robert "Bob" James Traill (1921–2004), a Canadian mineralogist and crystallographer who made significant contributions to the study of minerals from Mont Saint-Hilaire.

Properties

Mohs hardness: 5
Luster: Vitreous
Streak: White
Density: 3.03
Cleavage: None
Fracture: Uneven
Transparency: Transparent to translucent
Crystal system: Trigonal

Diagnostic features

## Identification Field identification of bobtraillite is practically impossible due to its microscopic size and resemblance to other minerals of the eudialyte group. Definitive identification requires advanced laboratory techniques, such as X-ray diffraction (XRD) and chemical analysis (EDS/WDS), which allow for the determination of its unique crystal structure and complex chemical composition. ## Distinguishing from Similar Minerals Bobtraillite is difficult to distinguish from other minerals of the eudialyte group, such as eudialyte itself, kentbrooksite, or oneillite, which occur in the same geological environment. The differences lie in subtle variations in chemical composition (especially in the content of sodium, strontium, and boron) and unit-cell parameters, which are not visible to the naked eye. ## Crystal Forms Bobtraillite crystallizes in the trigonal system, forming short, hexagonal (six-sided) prismatic crystals. Crystals are typically very small, not exceeding 1 mm, and often occur as single, well-formed grains in the rock.

Geological environment

## Genesis Bobtraillite is a magmatic mineral, crystallizing in the late stages from highly differentiated, silica-undersaturated alkaline magmas. It forms in nepheline syenite pegmatites, which are characterized by extreme enrichment in rare elements such as zirconium, strontium, niobium, and boron. ## Mineral Associations This mineral occurs in association with other rare minerals typical of nepheline syenites and their associated pegmatites. The most common associated minerals include: eudialyte, microcline, nepheline, aegirine, lorenzenite, astrophyllite, catapleiite, and manganoneptunite. ## Localities The only confirmed occurrence of bobtraillite worldwide is its type locality – the Poudrette quarry on Mont Saint-Hilaire, in the Montérégie region, Quebec, Canada. This is one of the most famous mineralogical localities in the world, known for the occurrence of over 400 different mineral species.

Rarity

Extremely rare

For collectors

## Quality Criteria The quality of a bobtraillite specimen is primarily assessed based on its existence and confirmed identity, due to its extreme rarity. The most desirable specimens are those with clearly visible, well-formed crystals, even if they are microscopic. Color contrast with the surrounding host rock (matrix) also enhances its visual and collector value. The clarity and transparency of the crystals are additional assets. ## Popular Localities The only source of bobtraillite specimens is the Poudrette quarry on Mont Saint-Hilaire in Canada. Specimens from this locality are highly prized by collectors specializing in rare minerals and systematic minerals, especially those originating from this particular mountain.

Care and storage

## Cleaning Due to its extreme rarity and fragility, bobtraillite specimens, typically occurring as microcrystals within the host rock, should not be cleaned mechanically or chemically. The safest method is to remove dust using a soft brush or a photographic air blower. ## What to Avoid Avoid contact with all chemicals, acids, and detergents. Do not subject it to ultrasonic cleaning. Protect from high temperatures and sudden temperature changes. Avoid impacts and shocks that could damage the delicate crystals. ## Storage Bobtraillite specimens should be stored under stable conditions, in enclosed "micromount" containers, to protect them from dust, moisture, and mechanical damage. It is best to store them in the dark to prevent potential degradation due to light.

Sources

IMA Mineral List (CNMNC)