Erionite series minerals in felsic volcanic rocks of southern Mesa Central, Guanajuato, Mexico
2021
Kshirsagar, Pooja | Miranda Avilés, Raul | Loza-Aguirre, Isidro | Li, Yanmei | Puy y Alquiza, María Jesús | Moncada-Sánchez, Cristina Daniela | Romo, Karen Arlete Navarro | Hernández-Jiménez, Athziri
Trace quantities of erionite series minerals were identified along with chabazite, clinoptilolite, and morderite within Chichindaro rhyolites (~ 30 Ma) at latitude 21°8′30″–21°17′00″ and longitude 101°5′00″–101°10′00″, ~ 15 km south of the present-day town of San Felipe in the state of Guanajuato, Mexico. Special attention was given to the erionite -K, Na, and Ca varieties. Despite their occurrence in trace amounts, image analyses of these minerals with the aid of Scanning Electron Microscope indicates the existence of both hair-like and needle-like fibers that are 5.85–29.26 μm long and 2.510–0.252 μm thick, which allows them to be categorized as “inhalable” (with length > 5 μm and thickness < 3 μm) that readily enters the respiratory tract of human and their livestock residing in this region. Chemical data along with the atomic% and apfu values obtained based on 72 oxygen atoms reveals that six crystals spots from SF-14-a and sample SF-12 show Si/(Si + Al) = 0.69–0.78, similar to the cancerogenic erionite identified at Tierra Blanca, Mexico; Lessini Mountains, NE Italy; Cappadocia, Turkey, and North Dakota, USA. However, these spots fail the E% and Mg content test. On the contrary, spots SF-14-2A, 2B, and 2C show Mg content in the range of 0.35–0.54 and balance error E% of − 2.90% (only in SF-14-2B) and pass the positive identification tests for erionites. Therefore, it is advisable to comment that the erionite series minerals identified within Chichindaro rhyolites area are of “undifferentiated” type and may not be carcinogenic.
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