Estudio mineralógico de diferentes prehnitas asociadas a rocas ofíticas de la provincia de Cádiz
- Salvador Domínguez Bella
- Matilde Forteza González
- Juan Cornejo Suero
- María Ángeles Álvarez Rodríguez
ISSN: 0210-6558
Year of publication: 1989
Volume: 12
Issue: 0
Pages: 179-187
Type: Article
More publications in: Boletín de la Sociedad Española de Mineralogía
Abstract
Different prehnites (generally radial aggregates) have been found associated to bassic subvolcanic rocks (ophites) of the southwest of the Subbetic zone (province of Cádiz), in Algodonales, Alcalá de los Gazules, Medina Sidonia and Conil. In the samples from Medina Sidonia the presence of hornblende (kaersutite) with needle-shaped crystals has been evidenced by X-ray diffraction. A comparative study by XRD, DTA-TG and IR spectroscopy has been carried out for those samples. The XRD results from samples heated at different temperatures were carefully discussed in order to evaluate the possibility of two structural domains P 2cm and P 2/n. Finally, no structural modifications have been detected from prehnite IR study below hydroxil loss temperature (about 750°C). The broad exotermic band observed by DTA-TG, between 20-400°C, has been attributed to a slight structural rearrangement.