Alfredcasparite

alfredcasparite

wesselsite

calzirtite

baghdadite

Images

Formula: Sr2TiO(Si2O7)
Sorosilicate (Si2O7 groups), strontium- and titanium- bearing mineral
Crystal system: Tetragonal
Specific gravity: 3.950 calculated
Hardness: 3 to 4
Streak: White
Colour: Colourless
Environments

Volcanic igneous environments
Metamorphic environments

Alfredcasparite is a new mineral, approved in 2023 and to date (May 2025) reported only from the type locality.

Localities

The type locality is Xenolith CS-034 (an alfredcasparite-bearing xenolith), Caspar quarry, Ettringen, Vordereifel, Mayen-Koblenz, Rhineland-Palatinate, Germany. The Caspar quarry is an open quarry and part of the Bellerberg volcano. The Bellerberg volcano is characterised by the presence of various thermally transformed xenoliths within leucite-tephrite lava, which differ due to the high-temperature metamorphism conditions and variable protolith composition. This leads to the formation of miscellaneous mineral assemblages, usually in the contact zones between xenolith and surrounding magma. The xenolith specimen containing alfredcasparite was about 30 × 20 × 20 cm3 in size. Alfredcasparite rarely forms flattened crystals up to 30 μm across; more common are irregular grains which do not exceed 15 μm in size.
The type material with alfredcasparite is highly diverse, especially in the case of rock-forming and accessory minerals. The main components of the analysed xenolith include sanidine, quartz, various pyroxenes like diopside-hedenbergite, aegirine, and less often clinoenstatite, wollastonite, titanite, gehlenite, fluorapatite and cuspidine. Additionally, iron-bearing wollastonite and highly iron-rich sanidine were also identified. Subordinately, wadalite, strontium-rich fluorapatite and minerals of the andradite-grossular and åkermanite-alumoåkermanite series were detected as well. The accessory minerals are represented by oxyspinel group minerals (spinel, magnetite, magnesioferrite), perovskite, chalcopyrite, zirconium-bearing minerals such as zircon, baddeleyite, and phases stoichiometrically (having its component elements present in the exact proportions indicated by its formula) corresponding to calzirtite, and baghdadite. In addition to alfredcasparite, two other strontium-bearing accessory phases were identified: a potentially new mineral with a chemical composition close to (Sr2Na)Ti(Si2Fe)Si2O14, and wesselsite. Moreover, the cavities and cracks of the xenolith are filled by secondary, low-temperature minerals such as fluorapophyllite-(K), calcite, fluorite, gismondine-Ca, baryte and celestine (Journal of Geosciences, 69.3.161-172).
Alfredcasparite from Xenolith CS-034 - Image

Back to Minerals