Mineral Database

Mineral Database
Mineralogy of Wales

Hastingsite

Crystal System: Monoclinic
Formula: NaCa2(Fe2+,Mg)4Fe3+(Si6Al2)O22(OH,Cl)2
Status of Occurrence: Confirmed Occurrence
Distribution: Locally Abundant
Chemical Composition: Sodium calcium iron magnesium aluminium silicate hydroxide
Method(s) of Verification: St David's Head - EMPA (Bevins, et al., 1994); Tan-y-Grisiau - polarizing microscope (Bromley, 1969).
Chemical Group:
  • Silicates
Geological Context:
  • Igneous
Introduction: hastingsite is an amphibole belonging to the calcic amphibole group. It occurs as a rock-forming mineral in basic igneous rocks.
Occurrence in Wales: as with many other ferro-magnesian minerals, hastingsite has only been confirmed from a few localities in Wales, although it is quite likely that it is more abundant than these reports reflect.
Key Localities:
There are no key localities for this specimen.
References:
  • Bevins, R.E., Lees, G.J. Roach, R.A. Rowbotham, G. & Floyd, P.A., 1994 Petrogenesis of the St David’s Head Layered Intrusion, Wales: a complex history of multiple magma injection and in situ crystallisation.  Transactions of the Royal Society of Edinburgh: Earth Sciences, 85, 91-121
  • Bromley, A.V., 1969 Acid plutonic igneous activity in the Ordovician of North Wales.  In: Wood, A. (ed.) The Pre-Cambrian and Lower Palaeozoic rocks of Wales. University of Wales Press, 387-408.
  • Roach, R.A., 1969 The composite nature of the St. David's Head and Carn Llidi intrusions of North Pembrokeshire.  In: Wood, A. (ed.) The Pre-Cambrian and Lower Palaeozoic rocks of Wales, University of Wales Press, Cardiff, 409-433.