Sierra Gorda Research Articles

Arsenic and mercury exposure in different insect trophic guilds from mercury mining areas in Mexico.

The exposure to arsenic and mercury in various insect trophic guilds from two mercury mining sites in Mexico was assessed. The two study sites were La Laja (LL) and La Soledad (LS) mines. Additionally, a reference site (LSR) was evaluated for LS. The terrestrial ecosystem was studied at LL, whereas both the terrestrial ecosystem and a stream called El Cedral (EC) were assessed at LS. The study sites are situated in the Biosphere Reserve Sierra Gorda (BRSG). Mercury vapor concentrations were measured with a portable analyzer, and concentrations of arsenic and mercury in environmental and biological samples were determined through atomic absorption spectrophotometry. Both pollutants were detected in all terrestrial ecosystem components (soil, air, leaves, flowers, and insects) from the two mines. The insect trophic guilds exposed included pollinivores, rhizophages, predators, coprophages, and necrophages. In LS, insects accumulated arsenic at levels 29 to 80 times higher than those found in specimens from LSR, and 10 to 46 times higher than those from LL. Similarly, mercury exposure in LS was 13 to 62 times higher than LSR, and 15 to 54 times higher than in LL. The analysis of insect exposure routes indicated potential exposure through air, soil, leaves, flowers, animal prey, carrion, and excrement. Water and sediment from EC exhibited high levels of arsenic and mercury compared to reference values, and predatory aquatic insects were exposed to both pollutants. In conclusion, insects from mercury mining sites in the BRSG are at risk.

Evaluación de las prácticas de conservación de suelo en la Subcuenca Presa Jalpan, Querétaro, México

This paper's main objective is to evaluate water erosion, and its effect on soil management and conservation practices in the subbasin Jalpan Dam, located at The Sierra Gorda Biosphere Reserve in the State of Queretaro in northern Mexico. This paper was elaborated in four stages: 1) Analysis of soil conservation practices at the study area, with information collected through semi-structured interviews and field verification; 2) Measurement of the effect in soil’s conservation practices on soil’s erodibility, by taking soil samples and in situ measurements on paired plots; 3) Estimation of water erosion and identification of priority areas for its management, by applying the USLE model of Wischmeier and Smith (1978) and the use of GIS (Geographic Information Systems); 4) Estimation of sediment contribution to the Jalpan dam, using the methodology of Aveldaño et al. (1994). As a result, 40 polygons with soil’s conservation practices were located within the Jalpan Dam sub-basin, distributed mainly in the high functional zone. 22 of the 40 polygons were visited, in which 6 types of practices were spotted: reforestations with pine-cedar, maguey lines, agricultural terraces, stone barriers, stone dams and brushwood check dams. The results show deterioration on the structures, more than 30% of them require maintenance and 20% are clogged. Vegetative practices have had little success, reflected in low plant densities and low survival. As a result of the conservation practices evaluations in soil’s erodibility, it was found that in 8 of the 9 sites evaluated, the practices decreased the susceptibility of the soil to erode. It is important to establish systematic supervising mechanisms to ensure proper evaluation of every soil conservation practice condition and function.

Polyphenolic Compounds and Antioxidant Capacity in Native Maize of the Sierra Gorda of Querétaro

Maize is part of the traditional diet of Mexico and other Latin American countries. The diverse varieties of maize produced by adaptation to different regions and climates are known as creole or native maize. The characteristics and nutritional contributions of each of these native maize are relatively diverse areas of study. This work specifically analyzes the nutritional aspects of creole maize grown in the Sierra Gorda in Querétaro. For this, a proximal chemical analysis was carried out, with a quantification of polyphenolic compounds and antioxidant capacities using the ABTS (2,20-azinobis (3-ethyl-benzothiazolin,6-sulfonic acid) and DPPH (2,2-difenil-1-picrilhidrazilo) methods to examine four landraces and one commercial hybrid control. The results indicate that, in general, the landraces present similar—and, in some cases, higher—nutritional indices than the commercial hybrid. With regard to polyphenolic compounds, the Elotes Occidentales and Tuxpeño varieties present greater amounts of total phenols and antiradical activity (ARA), as well as a higher concentration of flavonoids and percentage inhibition, respectively. Condensed tannins are identified both in the creole varieties and in the commercial hybrid. Creole maize presents important nutritional characteristics and can be a good source of antioxidant compounds, which can help the population as a source of food and in the prevention of chronic diseases.

The quinta huapanguera in the huapango arribeño and in the son huasteco: an ethnomusicological vision of this musical instrument in two traditional expressions

The quinta huapanguera is a type of Mexican guitar that is part of the instrumental ensemble that performs music in the Huasteca, which constitutes the main musical instrument of the son huasteco and the huapango arribeño. These two musical expressions are currently recreated in the Huasteca area and in the Sierra Gorda (San Luis Potosí, Querétaro, Hidalgo, Guanajuato, Tamaulipas, Veracruz, Puebla). The son huasteco and the huapango arribeño have common and different sociomusical features and functions. Therefore, the role of the quinta huapanguera varies, since it fulfills different rhythmic, harmonic and technical-musical functions, so comparing these roles will allow an analysis and systematization from a musicological perspective. Certain actions of individuals within sociocultural, historical and geopolitical contexts propitiate and define the existence of this sonorous instrument and the musical genres it performs. Identifying such anthropological issues will contribute to an understanding of the phenomena and codes that cause and make possible the genesis and development of musical instruments with their sonorous expressions. The ethnographic analysis that allows to see music as a cultural practice, the musical analysis that makes possible the definition of the structures and sonorous qualities of the quinta huapanguera and the two musical genres it plays, will allow to collect the necessary data and information to obtain a holistic vision of this sonorous instrument. The comparative analysis of the quinta huapanguera in both sonorous expressions, from the Ethnomusicology or also called Musical Anthropology, will contribute to the promotion of the cultural identity, since it will allow the understanding of these sociomusical phenomena.

Elevational and seasonal changes in a bird assemblage within a mountain system in central Mexico

Mountain systems around the world represent very important research models because they are hot spots for biological diversity. Understanding how animals communities change across environmental variation (e.g., elevational gradients) is central. Currently, the knowledge of the Mexican avian diversity is incomplete due to the absence of detailed studies and inventories in regions such as the mountainous systems of central Mexico. These surveys represent a simple and effective measure to estimate the diversity and perform as a basis for ecological research, as well as to determine priority areas for biological conservation. Here, we sampled 113 points divided into seven elevational segments ranging from 1000 to 3100 to assess differences along elevation and between seasons. We expected to find a gradual turnover of species, as well as a monotonic decrease in richness with respect to altitude. We obtained a total of 100 bird species representing 23% of the species registered for the state and 30% of the species registered for the Reserva de la Biosfera Sierra Gorda. We observed differences in species composition only in the extremes of the gradient. We recorded highest richness values towards the middle part of the gradient decreasing with elevation in winter. The results of this work contribute to increase the knowledge about bird diversity in the state of Querétaro, and highlights the importance of diversity analysis at different levels, such α and β diversity, through altitudinal clines.

Mammillaria monochrysacantha (Cactaceae), a new endemic species from Guanajuato, Mexico

A new species of Mammillaria ser. Stylothelae is described and illustrated. Mammillaria monochrysacantha is distinguished from other species of the series by having a globose stem with fibrous roots, one single golden yellow hooked central spine, 28–32 tortuous hair-like radial spines, flowers with lanceolate pale yellow tepals, and non-arilloid seeds. We provided a comparison with other morphologically close and sympatric species of Mammillaria. The new species is endemic from the Sierra Gorda, Guanajuato, Mexico. We included data about its habitat and the status of conservation. Additionally, we integrated an identification key for M. ser. Stylothelae from Guanajuato, San Luis Potosí, and Querétaro, Mexico.

Amphibians and reptiles of the Sierra Gorda de Querétaro Biosphere Reserve, Mexico: species richness, conservation status and comparison with other natural protected areas in central Mexico

The Sierra Gorda de Querétaro Biosphere Reserve (SGQBR) is one of the largest natural protected areas in Mexico; however, little is known about the richness and diversity of amphibians and reptiles. We present an updated list of species of both groups, the conservation status of these species, as well as an analysis of their diversity with respect to other protected natural areas (NPAs) in central Mexico. The SGQBR contains 132 herpetofauna species (35 amphibians and 97 reptiles). The richest and most diverse families for amphibians were Hylidae (anurans) and Plethodontidae (caudates), and for reptiles Phrynosomatidae (lizards), Colubridae and Dipsadidae (snakes). The values of taxonomic diversity of the SGQBR were similar to those for the regional pool considering others NPAs. However, it did not achieve the highest values compared to the adjacent Los Mármoles National Park or Sierra Gorda de Guanajuato Biosphere Reserve. There was a high complementarity in the species composition between El Chico National Park and SGQBR for both herpetofauna groups. Although a formal list is presented, it is necessary to carry out a greater number of studies focused on analyzing diversity, considering functional attributes of the species and the richness by vegetation types.

Mineralogy, petrology, and oxygen isotopic compositions of chondritic and achondritic lithologies in the anomalous CB carbonaceous chondrites Sierra Gorda 013 and Fountain Hills

AbstractThe CB (Bencubbin‐like) metal‐rich carbonaceous chondrites are subdivided into the CBa and CBb subgroups. The CBa chondrites are composed predominantly of ~cm‐sized skeletal olivine chondrules and unzoned Fe,Ni‐metal ± troilite nodules. The CBb chondrites are finer grained than the CBas and consist of chemically zoned and unzoned Fe,Ni‐metal grains, Fe,Ni‐metal ± troilite nodules, cryptocrystalline and skeletal olivine chondrules, and rare refractory inclusions. Both subgroups contain exceptionally rare porphyritic chondrules and no interchondrule fine‐grained matrix, and are interpreted as the products of a gas–melt impact plume formed by a high‐velocity collision between differentiated planetesimals about 4562 Ma. The anomalous metal‐rich carbonaceous chondrites, Fountain Hills and Sierra Gorda 013 (SG 013), have bulk oxygen isotopic compositions similar to those of other CBs but contain coarse‐grained igneous clasts/porphyritic chondrule‐like objects composed of olivine, low‐Ca‐pyroxene, and minor plagioclase and high‐Ca pyroxene as well as barred olivine and skeletal olivine chondrules. Cryptocrystalline chondrules, zoned Fe,Ni‐metal grains, and interchondrule fine‐grained matrix are absent. In SG 013, Fe,Ni‐metal (~80 vol%) occurs as several mm‐sized nodules; magnesiochromite (Mg‐chromite) is accessory; daubréelite and schreibersite are minor; troilite is absent. In Fountain Hills, Fe,Ni‐metal (~25 vol%) is dispersed between chondrules and silicate clasts; chromite and sulfides are absent. In addition to a dominant chondritic lithology, SG 013 contains a chondrule‐free lithology composed of Fe,Ni‐metal nodules (~25 vol%), coarse‐grained olivine and low‐Ca pyroxene, interstitial high‐Ca pyroxene and anorthitic plagioclase, and Mg‐chromite. Here, we report on oxygen isotopic compositions of olivine, low‐Ca pyroxene, and ±Mg‐chromite in Fountain Hills and both lithologies of SG 013 measured in situ using an ion microprobe. Oxygen isotope compositions of olivine, low‐Ca pyroxene, and Mg‐chromite in these meteorites are similar to those of magnesian non‐porphyritic chondrules in CBa and CBb chondrites: on a three‐isotope oxygen diagram (δ17O vs. δ18O), they plot close to a slope‐1 (primitive chondrule mineral) line and have a very narrow range of Δ17O (=δ17O–0.52 × δ18O) values, −2.5 ± 0.9‰ (avr ± 2SD). No isotopically distinct relict grains have been identified in porphyritic chondrule‐like objects. We suggest that magnesian non‐porphyritic (barred olivine, skeletal olivine, cryptocrystalline) chondrules in the CBas, CBbs, and porphyritic chondrule‐like objects in SG 013 and Fountain Hills formed in different zones of the CB impact plume characterized by variable pressure, temperature, cooling rates, and redox conditions. The achondritic lithology in SG 013 represents fragments of one of the colliding bodies and therefore one of the CB chondrule precursors. Fountain Hills was subsequently modified by impact melting; Fe,Ni‐metal and sulfides were partially lost during this process.

Two new micropterous species of the genus Sunius from Andalusia (Spain) (Coleoptera: Staphylinidae: Paederinae)

Two new species of the genus Sunius Stephens, 1829 are described from southern Spain: Sunius tricoliensis sp. nov. and Sunius lauxaensis sp. nov., both found in the same mountain massif, Sierra Gorda de Loja, Granada, Andalusia, but at different altitudes. Colour images of the adult habitus, forebody, sternite VIII, and aedeagus are provided for both species.

Promotion and implementation of Polish mining investments in foreign markets on the example of Latin America

Foreign investments are essential in deepening economic relations between the EU and Latin America. As Latin America is fortunate enough to have deposits of metals that have become particularly desirable due to the green industrial revolution, it remains one of the dominant directions of exploration and investment in the mining sector. To intensify cooperation within the mining industries based on their complementarity, common goals, and shared values, the EU-Latin America Mineral Development Network Platform was established for all entities relevant to the mining sector, not only authorities but also businesses (including SMEs) and scientific and research units. To create a common European understanding of best practices in the processing and mining of raw materials in terms of social, environmental, and economic performance, voluntary EU principles for sustainable raw materials have been developed. Moreover, many EU countries working on updating or implementing (Poland) mineral policies, and more and more EU and Polish mining companies have been reporting non-financial aspects and impacts on local development, also in foreign countries. At the end of 2022, the European Commission proposed a Critical Raw Materials Act: securing the new gas & oil at the heart of our economy initiative to enhance the diversification and supply of critical raw materials to Europe. So far, the largest Polish foreign investment is a copper mine in Sierra Gorda in Chile, owned by KGHM Polska Miedź SA together with the Japanese Sumitomo Group (from February 2022, Australian mining group South32). Even according to KGHM CEO, Marcin Chludziński, the Sierra Gorda mine had needed restructuring and now is a demanding but very satisfying project. KGHM reported that the revised EBITDA for 2021 was the highest and achieved PLN 10.3 billion (ca EUR 2.3 billion) year on year (+56%) and for the first time, Sierra Gorda began to pay off its liabilities towards the owners. Moreover, the mine received an award in the category of large producers awarded by the State Mining Association in Chile (SONAMI). In addition to mining activities in the field of exploration and exploitation of deposits, Poland is developing cooperation in technology (mining machinery) and education. To ensure sustainable extraction of raw materials additional skills are required, in particular in the area of management and social sciences. The aim of the paper is to analyze and identify factors and best practices enhancing international cooperation and the environmental sustainability of minerals in line with the 2030 Agenda for Sustainable Development on the example of Polish investments in Chile. The analyzed case studies in a broader context, including the EU and Polish mineral policy, allow for the development of certain recommendations and tools for the promotion of foreign investments in the mining industry.

Technical, economic and environmental analysis of solar thermochemical production of drop-in fuels

This study analyzes the technical performance, costs and life-cycle greenhouse gas (GHG) emissions of the production of various fuels using air-captured water and CO2, and concentrated solar energy as the source of high-temperature process heat. The solar thermochemical fuel production pathway utilizes a ceria-based redox cycle for splitting water and CO2 to syngas – a tailored mixture of H2 and CO – which in turn is further converted to liquid hydrocarbon fuels. The cycle is driven by concentrated solar heat and supplemented by a high-temperature thermal energy storage for round-the-clock continuous operation. The study examines three locations with high direct normal irradiation using a baseline heliostat field reflective area of 1 km2 for the production of six fuels, i.e. jet fuel and diesel via Fischer-Tropsch, methanol, gasoline via methanol, dimethyl ether, and hydrogen. Two scenarios are considered: near-term future by the year 2030 and long-term future beyond 2030.In the near-term future in Sierra Gorda (Chile), the minimum fuel selling price is estimated at around 76 €/GJ (2.5 €/L) for jet fuel and diesel, 65 €/GJ for methanol, gasoline (via methanol) and dimethyl ether (DME), and 42 €/GJ for hydrogen (excluding liquefaction). In the long-term future, with advancements in solar receiver, redox reactor, high-temperature heat recovery and direct air capture technologies, the industrial-scale plant could achieve a solar-to-fuel efficiency up to 13–19 %, depending on the target fuel, resulting in a minimum fuel selling price of 16–38 €/GJ (0.6–1.3 €/L) for jet fuel and diesel, and 14–32 €/GJ for methanol, gasoline, and DME, making these fuels synthesized from sunlight and air cost-competitive vis-à-vis e-fuels. To produce the same fuels in Tabernas (Spain) and Ouarzazate (Morocco) as in Sierra Gorda, the production cost would increase by 22–33 %. Greenhouse gas savings can be over 80 % already in the near-term future.

Study of Rb-Sr and Sm-Nd Isotopic Systems in Chondrules of the Sierra Gorda 009 and 013 Chondrites and Possible Mechanisms of Their Disturbance

Study of Rb-Sr and Sm-Nd Isotopic Systems in Chondrules of the Sierra Gorda 009 and 013 Chondrites and Possible Mechanisms of Their Disturbance

Frequency of Periodontal Disease and its Relationship with Age and with Comorbidities of the Metabolic Syndrome in Inhabitants Between 20 and 79 years of Age in the Sierra Gorda, Querétaro, Mexico

Aim To evaluate the frequency of periodontal disease and its relationship with age and the presence of metabolic syndrome in a group of patients from Sierra Gorda, Mexico. Methodology A descriptive, cross-sectional and prospective study was carried out in 208 patients between 20 and 79 years of age, of both sexes. Prior to the epidemiological survey, a Dentist Surgeon was calibrated (Kappa=0.91; p=001). To measure the presence of periodontal disease (PD), the Community Periodontal Index (IPC) was collected. To measure the association between the study variables, the Likelihood Ratio values were calculated because in all cases some of the observed values were ≤ 5, considering a confidence level of 95%. Results Both Diabetes and Dyslipidemia were the two comorbidities that occurred most frequently, observing that the older, the higher the probability of finding subjects with some type of comorbidity ( p=0.001 ). In patients who presented comorbidities, a higher frequency of moderate to severe gingivitis and mild periodontitis and cases of moderate to severe periodontitis were observed. Conclusion It is confirmed how aging and comorbidities are factors of great impact in the deterioration of tissues and dental support structures, which leads to a greater vulnerability to PD and its complications.

Bacterial diversity of an acid mine drainage beside the Xichú River (Mexico) accessed by culture-dependent and culture-independent approaches.

Xichú River is a Mexican river located in an environmental preservation area called Sierra Gorda Biosphere Reserve. Around it, there are tons of abandoned mine residues that represent a serious environmental issue. Sediment samples of Xichú River, visibly contaminated by flows of an acid mine drainage, were collected to study their prokaryotic diversity. The study was based on both cultural and non-cultural approaches. The analysis of total 16S rRNA gene by MiSEQ sequencing allowed to identify 182 Operational Taxonomic Units. The community was dominated by Pseudomonadota, Bacteroidota, "Desulfobacterota" and Acidobacteriota (27, 21, 19 and 16%, respectively). Different culture conditions were used focusing on the isolation of anaerobic bacteria, including sulfate-reducing bacteria (SRB) and arsenate-reducing bacteria (ARB). Finally, 16 strains were isolated. Among them, 12 were phylogenetically identified, with two strains being SRB, belonging to the genus Solidesulfovibrio ("Desulfobacterota"), while ten are ARB belonging to the genera Azospira (Pseudomonadota), Peribacillus (Bacillota), Raineyella and Propionicimonas (Actinomycetota). The isolate representative of Raineyella genus probably corresponds to a new species, which, besides arsenate, also reduces nitrate, nitrite, and fumarate.

Heterogenity of planetesimal collisional plume probed by glass inclusions in metal globules of Sierra Gorda 013, an unusual CBa‐like chondrite

AbstractMetal‐rich carbonaceous CB chondrites are generally assumed to be materials accreted from the gas–dust plume formed in catastrophic collisions of planetesimals, at least one of which was differentiated into a metal core and silicate shell. Micron‐sized inclusions of siliceous alkali‐rich glasses associated with sulfides were found in the metal globules of the Sierra Gorda 013 (SG 013), a CBa‐like chondrite. These inclusions are unusual carriers of volatile alkalis which are commonly depleted in CB chondrites. The inclusions are presented by two types: (1) Al‐bearing Nb‐poor glass associated with daubréelite and (2) Nb‐bearing Ca,Al,Mg‐poor glass associated with an unknown Na‐bearing Cr‐sulfide. The glass compositions do not correspond to equilibrium condensation, evaporation, or melting. The Nb‐bearing glass has a superchondritic Nb/Ta ratio (31) most likely indicating the fractionation of Nb and Ta in the high‐temperature gas–dust impact plume due to condensation from vapor or evaporation of precursor Nb‐rich particles. The glasses are interpreted as reaction products between refractory plume condensate particles (or possibly planetary or chondritic solids) with relatively low‐temperature K‐Na‐Si‐rich gas in oxidized conditions, possibly in a common plume vapor reservoir. Compositional differences indicate that the glasses and sulfides originated from several different sources under different fO2, fS2, andTconditions and were likely combined together and transported to the metal globule formation region by material flows in the heterogeneous impact plume. The glass–sulfide particles were enclosed in the globules aggregated from smaller solid or molten metal grains. The metal globules were further melted during transport to the high‐temperature plume region or by plume shockwave heating. Thus, the composition of the glasses, the host metal, and the main mass of SG 013 shows dynamic heterogeneity of physical conditions and impact plume composition after a large‐scale planetesimal collision.

The invasive Australian redclaw crayfish Cherax quadricarinatus Von Martens, 1868: a new threat for biodiversity in the Sierra Gorda Biosphere Reserve, Central Mexican Plateau

The invasive Australian redclaw crayfish Cherax quadricarinatus Von Martens, 1868: a new threat for biodiversity in the Sierra Gorda Biosphere Reserve, Central Mexican Plateau

Linajes de angiospermas endémicas en México: zonas de alto endemismo para la conservación

México está considerado como uno de los países megadiversos y en su territorio se encuentran entre 4 y 8% del número de total de especies de plantas del mundo, de las cuales 51% son endémicas. Existe una gran preocupación sobre la conservación de la flora mexicana, ya que se han detectado varias actividades y factores que la amenazan. En este trabajo se identifican áreas de endemismo para las angiospermas de México con el objetivo de priorizar regiones para conservación. Para categorizar estas zonas se sigue el enfoque que toma en cuenta la biodiversidad, el índice de endemismo ponderado y la historia evolutiva. Se identificaron los linajes de angiospermas, ya sean familias, géneros, o grupos infragenéricos con o sin estatus taxonómico que previamente se habían determinado como monofiléticos para representar la historia evolutiva en unidades espaciales equivalentes. Se construyó una base de datos de 9416 registros de especies de 259 grupos monofiléticos de angiospermas restringidas a México y se registró su presencia en estas áreas. Para cada una se calculó la riqueza de taxones y el índice de endemismo ponderado. Los resultados muestran que la mayoría de las zonas de más alto endemismo están en climas secos, con vegetación xérica, con dos excepciones de vegetación tropical y templada. Los índices de endemismo ponderado más altos se localizaron en: el área norte de matorral rosetófilo en Nuevo León y Coahuila, matorrales gipsófilos en San Luis Potosí, la Sierra Gorda en Querérato, Tolantongo en Hidalgo, el Valle de Tehuacán-Cuicatlán en Puebla y Oaxaca, El Salto en Durango, la Sierra de Quila en Jalisco, la zona oeste de la Depresión del Balsas en Michoacán, Guerrero, Morelos y el Estado de México, la zona de Tehuantepec en Oaxaca y El Triunfo en Chiapas. Algunas áreas de endemismo en el Desierto Chihuahuense, en la Cuenca del Balsas y en la Depresión de Chiapas, así como del sur de Oaxaca no están suficientemente protegidas. Se registraron aproximadamente 340 especies con distribución restringida a un solo cuadrante y de éstas la mayoría de las que se incluyen en la lista de taxones amenazados de México pertenecen a las Cactaceae.

Pohlite, a new lead iodate hydroxide chloride from Sierra Gorda, Chile

AbstractThe new mineral pohlite (IMA2022–043), Pb7(IO3)(OH)4Cl9, was found at La Compania mine, Sierra Gorda, Antofagasta Province, Antofagasta, Chile, where it occurs in cavities in an oxidised portion of a quartz vein in association with massive aragonite and anhydrite. Pohlite crystals are transparent, colourless to pale grey blades, up to 4 mm in length. The mineral has a white streak, adamantine lustre and is nonfluorescent. It is brittle with irregular, conchoidal fracture. The Mohs hardness is ~2½ and it has no cleavage. The calculated density is 5.838(2) g cm–3. Optically, the mineral is biaxial (+) with α < 2.01(est.), β = 2.02 (calc.), γ = 2.05 (calc.); 2V = 60(5)°; moderate r > v dispersion; orientation: Y∧a ≈ 20°, Z∧b ≈ 30°; and is nonpleochroic. The Raman spectrum exhibits bands consistent with IO3– and O–H. Electron microprobe analysis provided the empirical formula Pb6.74I1.00Cl9.29O6.71H4.23. The five strongest powder X-ray diffraction lines are [dobs Å(I)(hkl)]: 3.818(91)(023, 122, 1$\bar{2}$1), 3.674(85)($\bar{1}\bar{2}$1, $\bar{1}$22, 200, 104), 3.399(47)($\bar{2}$10, 210, $\bar{1}$04), 2.378(100)(302, 041, $\bar{2}$24) and 1.9943(45)(multiple). Pohlite is triclinic, P$\bar{1}$, a = 7.3366(5), b = 9.5130(9), c = 16.2434(15) Å, α = 81.592(7), β = 84.955(7), γ = 89.565(6)°, V = 1117.13(17) Å3 and Z = 2. The structure of pohlite (R1 = 0.0328 for 3394 I > 2σI) contains two types of clusters, a [Pb4(OH)3]5+ cluster formed by short Pb–O bonds and a [Pb3(OH)(IO3)]28+ ‘double cluster’ formed by short I–O bonds and short- to medium-length Pb–O bonds. Long Pb–Cl and I–Cl bonds link the clusters together in three dimensions.

El búho cara oscura (Asio stygius), nuevo registro para la avifauna del estado de Querétaro, México

Reportamos el primer registro del búho cara oscura (Asio stygius) para el estado de Querétaro. El registro corresponde a un individuo que fue herido y decomisado en el municipio de Landa de Matamoros, en el interior de la Reserva de la Biosfera Sierra Gorda. Esta observación refuerza la hipótesis de una distribución extendida de A. stygius a través de la parte septentrional de la Sierra Madre Oriental.

Succulent Conservation in the Sierra Gorda of Querétaro: the Impact of Feral Burros and Goats

Succulent Conservation in the Sierra Gorda of Querétaro: the Impact of Feral Burros and Goats