Next Article in Journal
Effect of Sodium Chloride Concentration on Saturated Permeability of Remolded Loess
Previous Article in Journal
Mineral Processing and Metallurgical Treatment of Lead Vanadate Ores
Open AccessArticle

Agates from Western Atlas (Morocco)—Constraints from Mineralogical and Microtextural Characteristics

Faculty of Geology, Geophysics and Environmental Protection, AGH UST, University of Science and Technology, 30 Mickiewicz Av., 30-059 Krakow, Poland
Author to whom correspondence should be addressed.
Minerals 2020, 10(2), 198;
Received: 13 January 2020 / Revised: 18 February 2020 / Accepted: 19 February 2020 / Published: 22 February 2020
(This article belongs to the Special Issue Agates: Types, Mineralogy, Deposits, Host Rocks, Ages and Genesis)
Agate samples collected from the vicinity of Asni and Agouim (Western Atlas, Morocco) were investigated using microscopic observations supported by Raman micro-spectroscopy. The agates are marked by the presence of various microtextures typical of epithermal vein deposits, including jigsaw-puzzle, feathery, and lattice-bladed. The first two indicate that the formation of agates was likely marked by recrystallization of metastable silica phases (i.e., opaline silica or massive chalcedony). The presence of lattice-bladed (after barite and calcite) quartz may be, in turn, ascribed to the boiling-related conditions that could have triggered the formation of abundant copper and iron sulfides found within silica matrix. Additionally, the local occurrence of growth lines (so-called Bambauer quartz) and intergrowth of length-slow and length-fast chalcedony are linked to the variations of physico-chemical conditions during rock formation (alkaline-acidic). According to Raman spectroscopy, silica matrix of the agates is made of α-quartz with a local admixture of moganite (from 0.0 up to 78 wt.%), but also contains numerous solid inclusions of hematite, celadonite, as well as poorly-organized carbonaceous material and rutile. These phases were likely emplaced during low-temperature hydrothermal activity of SiO2-bearing fluids that originated from post-magmatic hydrothermal activity developed within host rocks and/or meteoric waters. View Full-Text
Keywords: Moroccan agates; ore minerals; microtexture; moganite; Raman spectra Moroccan agates; ore minerals; microtexture; moganite; Raman spectra
Show Figures

Figure 1

MDPI and ACS Style

Pršek, J.; Dumańska-Słowik, M.; Powolny, T.; Natkaniec-Nowak, L.; Toboła, T.; Zych, D.; Skrepnicka, D. Agates from Western Atlas (Morocco)—Constraints from Mineralogical and Microtextural Characteristics. Minerals 2020, 10, 198.

Show more citation formats Show less citations formats
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Access Map by Country/Region

Back to TopTop