Chabazite-Sr

Chemical formula: (Sr,Ca)₂Al₄Si₈O₂₄·₁₁H₂O

Chabazite-Sr is a rare zeolite from the chabazite group, distinguished by the dominance of strontium in its chemical composition and forming vitreous, colorless or yellowish crystals.

## Characteristics Chabazite-Sr is a mineral from the zeolite group, belonging to the chabazite series. It is the strontium analogue of chabazite-Ca and chabazite-Na. It typically forms well-developed, pseudorhombohedral or cubic crystals, which often show striations on their faces. Specimens are usually small, reaching several millimeters. It is a transparent to translucent mineral with a vitreous luster. ## Physical Properties Its Mohs hardness is 4-4.5, making it a relatively soft mineral. The density is low, approximately 2.16 g/cm³, which is typical for zeolites. It exhibits poor cleavage in one direction. ## Colors and Varieties Chabazite-Sr occurs in a limited color range. It is most often colorless, sometimes pale yellow. No named color or commercial varieties are distinguished. ## History and Name The mineral's name refers to its connection with other minerals from the chabazite group and to the dominant element in its composition – strontium (Sr). It was recognized as a distinct mineral species by the International Mineralogical Association (IMA) in 1998. Its discovery is associated with a pegmatite on Mount Suoluaiv in the Lovozero Massif in Russia. ## Uses Chabazite-Sr, like other rare zeolites, has no industrial significance. However, it is sought after and valued by collectors specializing in rare minerals, zeolites, and minerals from specific localities, especially from its type locality.

Properties

Mohs hardness: 4-4.5
Luster: Vitreous
Streak: White
Density: 2.16
Cleavage: On (101)
Fracture: Uneven
Transparency: Transparent to translucent
Crystal system: Trigonal

Diagnostic features

## Identification Chabazite-Sr is difficult to identify unambiguously by visual inspection. Its characteristic, pseudorhombohedral crystals with a vitreous luster are an important clue. Its occurrence in paragenesis typical of nepheline syenite pegmatites can also aid identification. However, definitive identification requires advanced analytical methods, such as chemical analysis (EDS) to confirm strontium dominance. ## Distinguishing from similar minerals It can be easily confused with other minerals from the chabazite group, such as chabazite-Ca, chabazite-Na, or chabazite-K. Visual differentiation is practically impossible. Other zeolites, such as some forms of analcime or phillipsite, may also have a similar appearance. It differs from them in crystal form and environment of occurrence, but ultimate distinction requires chemical composition analysis. ## Crystal forms It most often forms single, well-developed crystals with a shape similar to a rhombohedron or cube (pseudorhombohedra). Crystals often occur as penetration twins. Less commonly, it forms granular aggregates or radial aggregates.

Geological environment

## Genesis Chabazite-Sr is a mineral of hydrothermal origin. It forms in the late stages of crystallization in vugs and fissures within alkaline pegmatites, especially nepheline syenite pegmatites. It crystallizes from strontium-rich solutions at relatively low temperatures. ## Mineral associations This mineral co-occurs with other rare minerals typical of the Lovozero and Khibiny massifs' pegmatites. Its typical associations include: lorenzenite, eudialyte, lamprophyllite, natrolite, aegirine, microcline, nepheline, and other zeolites. ## Localities The most important and type locality for chabazite-Sr is seidozerite pegmatite No. 1 on Mount Suoluaiv in the Lovozero Massif, Kola Peninsula, Russia. This is the locality from which the best-formed and most commonly encountered specimens originate. Outside Russia, its occurrence has also been reported in the Poudrette quarry at Mont Saint-Hilaire in Quebec (Canada), another classic locality for rare alkaline minerals.

Rarity

Very rare

For collectors

## Quality Criteria The most prized chabazite-Sr specimens are characterized by sharp, well-formed crystals with distinct luster and good transparency. Specimens where crystals are embedded in a contrasting rock matrix, accompanied by other rare minerals, are highly valued. Crystal size is also an important factor – specimens with crystals exceeding several millimeters are considered exceptional. ## Popular Localities By far the most desired and classic locality for chabazite-Sr collectors is its type locality – the Lovozero Massif in Russia. Specimens from Mont Saint-Hilaire in Canada are also valued, but generally rarer on the market and often with smaller crystals.

Care and storage

## Cleaning Specimens should be cleaned very carefully, using a soft brush to remove dust. If washing is necessary, use only distilled water, applied gently. Ultrasonic cleaners should be avoided, as they can damage fragile crystals. ## What to avoid Avoid contact with acids and other chemicals that may react with the mineral. Chabazite-Sr is sensitive to high temperatures, which can cause dehydration and destruction of the crystal. It should be protected from prolonged exposure to direct sunlight and sudden temperature changes. ## Storage Chabazite-Sr specimens are best stored in separate, sealed display boxes to protect them from dust and mechanical damage. Due to its fragility, it should not be stored in contact with harder minerals.