Dissolution of K-feldspar into Si-Al gel and crystallization of halloysite identified in the kaolin deposit of Sao Vicente de Pereira (Portugal)

• Type: Article in International Scientific Journal
• Date: 2000

Authors

Bobos, I (Author) Other; Gomes, C (Author) Other

Journal

Title: Geologica Carpathica

Vol. 51

Pages: 49-57

ISSN: 1335-0552

Publisher: The Earth Science Institute of SAS

Indexing

ISI Web of Knowledge - 2 Citations

Scopus - 3 Citations

Scientific classification

FOS: Natural sciences > Earth and related Environmental sciences

Other information

Authenticus ID: P-001-0WY

Abstract (EN): Dissolution of K-feldspar into Si-Al non-crystalline phase was identified in the kaolin deposit of Sao Vicente de Pereira (Portugal). The gel having a SiO2/Al2O3 ratio approximately equal to the unity, crystallized into halloysite-0.7 nm. SEM investigations carried out on K-feldspar grains show a vacuolar texture characterized by etch-pits of various dimensions. The pits exhibit various shapes, either polygonal or circular. The gel was identified by SEM on the K-feldspar surfaces and by TEM in the < 2 mu m clay fractions. TEM images display tubes of halloysite-0.7 nm surrounding flakes of SI-AI gel. Relicts of K-feldspar pseudomorphs submitted to amorphization are identified by TEM. SAED analyses confirmed the non-crystalline state of the gel. Electron microprobe analyses attested a very fast destabilization of the chemical structure of K-feldspar grains.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 9