Perovskite

Crystal System: Orthorhombic
Status of Occurrence: Unconfirmed Occurrence
Distribution: Rare
Chemical Composition: Calcium titanium oxide
Chemical Formula: CaTiO3
Method(s) of Verification: all occurrences - visual/polarizing microscope identification.

Chemical Group:

  • Oxides & Hydroxides

Geological Context:

  • Igneous
  • Igneous/metamorphic extraterrestrial
Introduction: perovskite occurs as an accessory mineral in basic and alkaline igneous rocks, often forming as an alteration product, such as in rims around ilmenite. It is also found in contact metamorphosed impure limestones and is known from chondritic meteorites (Deer et al., 1992).
Occurrence in Wales: three occurrences of perovskite are noted in the literature, although as these are all early accounts (Elsden, 1904; Greenly, 1919; Williams, 1927) it is highly likely that all these descriptions refer to titanite. Elsden (1904) noted perovskite crystals replacing ilmenite in altered dolerite dykes of the Llyn Padarn area of Gwynedd. These appear to have the optical characteristics of perovskite, although Elsden (1904) did state that a positive identification could not be based on optical determination alone. If verified this would represent the first recorded occurrence of perovskite in the British Isles. Similarly, Greenly (1919) also makes a rather dubious description of perovskite in altered pyroxenites and gabbros from the Precambrian rocks in Anglesey. A third account was reported by Williams (1927) who noted colourless perovskite in association with chlorite in altered palagonite tuffs in the vicinity of Snowdon, such as near the head of the Afon Glaslyn at the head of the Cwm Dyli.

Key Localities:

There are no key localities for this specimen.

References:

  1. Elsden, J.V., 1904. On the age pf the Llyn-Padarn dykes. Quarterly Journal of the Geological Society of London, 60, 372-388.
  2. Greenly, E., 1919. The Geology of Anglesey. Memoirs of the Geological Survey of Great Britain, 980pp (2 volumes).
  3. Williams, H., 1927. The geology of Snowdon (North Wales). Quarterly Journal of the Geological Society of London, 83, 346-431.