Holtite and Dumortierite from the Szklary Pegmatite, Lower Silesia, Poland

The Szklary holtite is represented by three compositional varieties: (I) Ta-bearing (up to 14.66 wt.% Ta(2)O(5)), which forms homogeneous crystals and cores within zoned crystals; (2) Ti-bearing (up to 3.82 wt.% TiO(2)), found as small domains within the core; and (3) Nb-bearing (up to 5.30 wt.% Nb(2)O(5),) forming the rims of zoned crystals. All three varieties show variable Sb+As content, reaching 19.18 wt.% Sb(2)O(3) (0.87 Sb a.p.f.u.) and 3.30 wt.% As(2)O(3) (0.22 As a.p.f.u.) in zoned Ta-bearing holtite, which constitutes the largest Sb+As content reported for the mineral. The zoning in holtite is a result of Ta-Nb fractionation in the parental pegmatite-forming melt together with contamination of the relatively thin Szklary dyke by Fe, Mg and Ti. Holtite and the As- and Sb-bearing dumortierite, which in places overgrows the youngest Nb-bearing zone, suggest the following crystallization sequence: Ta-bearing holtite -\u3e Ti-bearing holtite -\u3e Nb-bearing holtite -\u3e As- and Sb-bearing, (Ta,Nb,Ti)-poor dumortierite -\u3e As- and Sb-dominant, (Ta,Nb,Ti)-free dumortierite-like mineral (16.81 wt.% As(2)O(3) and 10.23 wt.% Sb(2)O(3)) with (As+Sb) \u3e Si. The last phase is potentially a new mineral species, Al(6)rectangle B(Sb,As)(3)O(15). or Al(5)rectangle(2)B(Sb,As)(3)O(12)(OH)(3), belonging to the dumortierite group. The Szklary holtite shows no evidence of clustering of compositions around \u27holtite I\u27 and \u27holtite II\u27. Instead, the substitutions of Si(4+) by Sb(3+)+As(3+) at the Si/Sb sites and of Ta(5+) by Nb(5+) or Ti(4+) at the Al(l) site suggest possible solid solutions between: (1) (Sb,As)-poor and (Sb,As)-rich holtite; (2) dumortierite and the unnamed (As+Sb)-dominant dumortierite-like mineral; and (3) Ti-bearing dumortierite and holtite, i.e. our data provide further evidence for miscibility between holtite and dumortierite, but leave open the question of defining the distinction between them. The Szklary holtite crystallized from the melt along with other primary Ta-Nb-(Ti) minerals such as columbite-(Mn), tantalite-(Mn), stibiotantalite and stibiocolumbite as the availability of Ta decreased. The origin of the parental melt can be related to anatexis in the adjacent Sowie Mountains complex, leading to widespread migmatization and metamorphic segregation in pelitic-psammitic sediments metamorphosed at similar to 390-380 Ma

Emerald and Aquamarine Mineralization in Canada

This paper reviews the geology, mineralogy, and origin of the gem varieties of beryl, including emerald (green) and aquamarine (blue); it focuses on western Canada, especially the Yukon Territory, because this is where most of the recent discoveries have been made. However, emerald occurrences in Ontario are also considered, including Canada's first reported discovery in 1940. Beryl (B3Al2Si6O18) is relatively common and spatially associated with granites and granitic pegmatites, but emerald is rare because trace amounts of Cr and/or V are required (to replace Al in the crystal structure) and these elements generally do not occur in sufficient concentrations in granitic rocks. The geological conditions needed to bring Be into contact with Cr and/or V are briefly discussed, as are the factors to consider and techniques to use in exploring for gem-quality beryl. SUMMAIRE Le présent article traite de la géologie, de la minéralogie et de l'origine de variétés gemmifères de béryl (vert), dont l'émeraude et l'aigue-marine (bleue). Il traite principalement de l'Ouest canadien, particulièrement du Territoire du Yukon, région où la plupart des découvertes ont eu lieu. Toutefois, des découvertes faites en Ontario sont aussi considérées, incluant la première au Canada, en 1940. Le Béryl (B3Al2Si6O18) est relativement commun et associé aux granites et aux pegmatites granitiques, mais l'émeraude est rare parce qu'elle nécessite le remplacement de l'Al dans la structure cristalline du béryl par du Cr et/ou du V, et ces éléments ne se retrouvent généralement pas dans en concentrations suffisantes dans les roches granitiques. Les facteurs géologiques nécessaires pour que le Be et le Cr et/ou le V soient mis en contact font l'objet de discussion, tout comme les facteurs à considérer et les techniques à employer dans l'exploration de gisements de béryls gemmifères

The Crystal Chemistry of Holtite

Holtite, approximately (Al,Ta,square)Al(6)(BO(3))(Si,Sb(3+),As(3+))(Sigma 3)O(12)(O,OH,square)(Sigma 3), is a member of the dumortierite group that has been found in pegmatite, or alluvial deposits derived from pegmatite, at three localities: Greenbushes, Western Australia; Voron\u27i Tundry, Kola Peninsula, Russia; and Szklary, Lower Silesia, Poland. Holtite can contain \u3e30 wt.% Sb(2)O(3), As(2)O(3), Ta(2)O(5), Nb(2)O(5), and TiO(2) (taken together), but none of these constituents is dominant at a crystallographic site, which raises the question whether this mineral is distinct from dumortierite. The crystal structures of four samples from the three localities have been refined to R(1) = 0.02-0.05. The results show dominantly: Al, Ta, and vacancies at the Al(1) position; Al and vacancies at the Al(2), (3) and (4) sites; Si and vacancies at the Si positions; and Sb, As and vacancies at the Sb sites for both Sb-poor (holtite I) and Sb-rich (holtite II) specimens. Although charge-balance calculations based on our single-crystal structure refinements suggest that essentially no water is present, Fourier transform infrared spectra confirm that some OH is present in the three samples that could be measured. By analogy with dumortierite, the largest peak at 3505-3490 cm(-1) is identified with OH at the O(2) and O(7) positions. The single-crystal X-ray refinements and FTIR results suggest the following general formula for holtite: Al(7-[5x+y+z]/3)(Ta,Nb)(x)square([2x+y+z]/3)BSi(3-y)(Sb,As)(y)O(18-y-z)(OH)(z), where x is the total number of pentavalent cations, y is the total amount of Sb + As, and z \u3c= y is the total amount of OH. Comparison with the electron microprobe compositions suggests the following approximate general formulae Al(5.83)(Ta,Nb)(0.50)square(0.67)BSi(2.50)(Sb,As)(0.50)O(17.00)(OH)(0.50) and Al(5.92)(Ta,Nb)(0.25)square(0.83)BSi(2.00)(Sb,As)(1.00) O(16.00)(OH)(1.00) for holtite I and holtite II respectively. However, the crystal structure refinements do not indicate a fundamental difference in cation ordering that might serve as a criterion for recognizing the two holtites as distinct species, and anion compositions are also not sufficiently different. Moreover, available analyses suggest the possibility of a continuum in the Si/(Sb + As) ratio between holtite I and dumortierite, and at least a partial continuum between holtite I and holtite II. We recommend that use of the terms holtite I and holtite II be discontinued

The dumortierite supergroup. I. A new nomenclature for the dumortierite and holtite groups

Although the distinction between magnesiodumortieite and dumortierite, i.e. Mg vs. Al dominance at the partially vacant octahedral Al1 site, had met current criteria of the IMA Commission on New Minerals, Nomenclature and Classification (CNMNC) for distinguishing mineral species, the distinction between holtite and dumortierite had not, since Al and Si are dominant over Ta and (Sb, As) at the Al1 and two Si sites, respectively, in both minerals. Recent studies have revealed extensive solid solution between Al, Ti, Ta and Nb at Al1 and between Si, As and Sb at the two Si sites or nearly coincident (As, Sb) sites in dumortierite and holtite, further blurring the distinction between the two minerals. This situation necessitated revision in the nomenclature of the dumortierite group. The newly constituted dumortierite supergroup, space group Pnma (no. 62), comprises two groups and six minerals, one of which is the first member of a potential third group, all isostructural with dumortierite. The supergroup, which has been approved by the CNMNC, is based on more specific end-member compositions for dumortierite and holtite, in which occupancy of the Al1 site is critical. (1) Dumortierite group, with Al1 = Al^(3+), Mg^(2+) and 〈, where 〈 denotes cation vacancy. Charge balance is provided by OH substitution for O at the O2, O7 and O10 sites. In addition to dumortierite, endmember composition AlAl_6Bsi_3O_(18), and magnesiodumortierite, endmember composition MgAl_6Bsi_3O_(17)(OH), plus three endmembers, “hydroxydumortierite”, 〈Al_6Bsi_3O_(15)(OH)_3 and two Mg-Ti analogues of dumortierite, (Mg_(0.5)Ti_(0.5))Al_6Bsi_3O_(18) and (Mg_(0.5)Ti_(0.5))Mg_2Al_4Bsi_3O_(16)(OH)_2, none of which correspond to mineral species. Three more hypothetical endmembers are derived by homovalent substitutions of Fe^(3+) for Al and Fe^(2+) for Mg. (2) Holtite group, with Al1 = Ta^(5+), Nb^(5+), Ti^(4+) and 〈. In contrast to the dumortierite group, vacancies serve not only to balance the extra charge introduced by the incorporation of pentavalent and quadrivalent cations for trivalent cations at Al1, but also to reduce repulsion between the highly charged cations. This group includes holtite, endmember composition (Ta_(0.6)〈_(0.4))Al_6Bsi_3O_(18), nioboholite (2012-68), endmember composition (Nb_(0.6)〈_(0.4_)Al_6Bsi_3O_(18), and titanoholtite (2012-69), endmember composition (Ti_(0.75)〈_(0.25))Al_6Bsi_3O_(18). (3) Szklaryite (2012-70) with Al1 = 〈 and an endmember formula 〈Al_6Bas^(3+)_ 3O_(15). Vacancies at Al1 are caused by loss of O at O2 and O7, which coordinate the Al1 with the Si sites, due to replacement of Si^(4+) by As^(3+) and Sb^(3+), and thus this mineral does not belong in either the dumortierite or the holtite group. Although szklaryite is distinguished by the mechanism introducing vacancies at the Al1 site, the primary criterion for identifying it is based on occupancy of the Si/As, Sb sites: (As^(3+) + Sb^(3+)) > Si^(4+) consistent with the dominant-valency rule. A Sb^(3+) analogue to szklaryite is possible

The dumortierite supergroup. II. Three new minerals from the Szklary pegmatite, SW Poland: Nioboholtite, (Nb_(0.6)〈_(0.4))Al_6Bsi_3O_(18), titanoholtite, (Ti_(0.75)〈_(0.25))Al_6Bsi_3O_(18), and szklaryite 〈Al_6Bas^(3+)_ 3O_(15)

Three new minerals in the dumortierite supergroup were discovered in the Szklary pegmatite, Lower Silesia, Poland. Nioboholtite, endmember (Nb_(0.6)〈_(0.4))Al_6B_3Si_3O_(18), and titanoholtite, endmember (Ti_(0.75)〈_(0.25))Al_6B_3Si_3O_(18), are new members of the holtite group, whereas szklaryite, endmember 〈Al_6Bas^(3+)_ 3O_(15), is the first representative of a potential new group. Nioboholtite occurs mostly as overgrowths not exceeding 10 μm in thickness on cores of holtite. Titanoholtite forms patches up to 10 μm across in the holtite cores and streaks up to 5 μm wide along boundaries between holtite cores and the nioboholtite rims. Szklaryite is found as a patch ∼2 μm in size in As- and Sb- bearing dumortierite enclosed in quartz. Titanoholtite crystallized almost simultaneously with holtite and other Ta-dominant minerals such as tantalite-(Mn) and stibiotantalite and before nioboholtite, which crystallized simultaneously with stibiocolumbite during decreasing Ta activity in the pegmatite melt. Szklaryite crystallized after nioboholtite during the final stage of the Szklary pegmatite formation. Optical properties could be obtained only from nioboholtite, which is creamy-white to brownish yellow or grey-yellow in hand specimen, translucent, with a white streak, biaxial (–), n_α = 1.740 – 1.747, n_β ∼ 1.76, n_γ ∼ 1.76, and Δ < 0.020. Electron microprobe analyses of nioboholtite, titanoholtite and szklaryite give, respectively, in wt.%: P_2O_5 0.26, 0.01, 0.68; Nb_2O_55.21, 0.67, 0.17; Ta_2O_5 0.66, 1.18, 0.00; SiO_2 18.68, 21.92, 12.78; TiO_2 0.11, 4.00, 0.30; B_2O_3 4.91, 4.64, 5.44; Al_2O_3 49.74, 50.02, 50.74; As_2O_3 5.92, 2.26, 16.02; Sb_2O_3 10.81, 11.48, 10.31; FeO 0.51, 0.13, 0.19; H_2O (calc.) 0.05, –, –, Sum 96.86, 96.34, 97.07, corresponding on the basis of O = 18–As–Sb to {(Nb_(0.26)Ta_(0.02)〈_(0.18)) (Al_(0.27)Fe_(0.05)Ti_(0.01))〈_(0.21)}_(Σ1.00)Al_6B_(0.92){Si_(2.03)P_(0.02)(Sb_(0.48)As_(0.39)Al_(0.07)}_(Σ3.00)(O_(17.09)OH_(0.04)〈_(0.87))_(Σ18.00), {(Ti_(0.32) Nb_(0.03)Ta_(0.03)〈_(0.10) )(Al_(0.3 5) Ti_(0.01) Fe_(0.01))〈_(0.15)}_(Σ1.00) Al_6 B_(0.86) {Si_(2.36) (Sb_(0.51) As_(0.14) )}_(Σ3.01)(O_(17.35)〈_(0.65))_(Σ18.00) and {〈_(0.53) (Al_(0.41) Ti_(0.02) Fe_(0.02))(Nb_(0.01)〈_(0.01) )}_(Σ1.00)Al_6 B_(1.01) {(As_(1.07) Sb_(0.47) Al_(0.03)) Si_(1.37) P_(0.06)}_(Σ3.00)(O_(16.46)〈_(1.54))_(Σ18.00). Electron backscattered diffraction indicates that the three minerals are presumably isostructural with dumortierite, that is, orthorhombic symmetry, space group Pnma (no. 62), and unit-cell parameters close to a = 4.7001, b = 11.828, c = 20.243 Å, with V = 1125.36 Å^3 and Z = 4; micro-Raman spectroscopy provided further confirmation of the structural relationship for nioboholtite and titanoholtite. The calculated density is 3.72 g/cm^3 for nioboholtite, 3.66 g/cm^3 for titanoholtite and 3.71 g/cm^3 for szklaryite. The strongest lines in X-ray powder diffraction patterns calculated from the cell parameters of dumortierite of Moore and Araki (1978) and the empirical formulae of nioboholtite, titanoholtite and szklaryite are [d, Å, I (hkl)]: 10.2125, 67, 46, 19 (011); 5.9140, 40, 47, 57 (020); 5.8610, 66, 78, 100 (013); 3.4582, 63, 63, 60 (122); 3.4439, 36, 36, 34 (104); 3.2305, 100, 100, 95 (123); 3.0675, 53, 53, 50 (105); 2.9305, 65, 59, 51 (026); 2.8945, 64, 65, 59 (132), respectively. The three minerals have been approved by the IMA CNMNC (IMA 2012-068, 069, 070) and were named for their relationship to holtite and occurrence in the Szklary pegmatite, respectively

A holistic multi-methodology for sustainable renovation

A review of the barriers for building renovation has revealed a lack of methodologies, which can promote sustainability objectives and assist various stakeholders during the design stage of building renovation/retrofitting projects. The purpose of this paper is to develop a Holistic Multi-methodology for Sustainable Renovation, which aims to deal with complexity of renovation projects. It provides a framework through which to involve the different stakeholders in the design process to improve group learning and group decision-making, and hence make the building renovation design process more robust and efficient. Therefore, the paper discusses the essence of multifaceted barriers in building renovation regarding cultural changes and technological/physical changes. The outcome is a proposal for a multi-methodology framework, which is developed by introducing, evaluating and mixing methods from Soft Systems Methodologies (SSM) with Multiple Criteria Decision Making (MCDM). The potential of applying the proposed methodology in renovation projects is demonstrated through a case study

Parental Feeding Practices in Mexican American Families: Initial Test of an Expanded Measure

Background: Although obesity rates are high among Latino children, relatively few studies of parental feeding practices have examined Latino families as a separate group. Culturally-based approaches to measurement development can begin to identify parental feeding practices in specific cultural groups. This study used qualitative and quantitative methods to develop and test the Parental Feeding Practices (PFP) Questionnaire for use with Mexican American parents. Items reflected both parent’s use of control over child eating and child-centered feeding practices. Methods: In the qualitative phase of the research, 35 Latino parents participated in focus groups. Items for the PFP were developed from focus group discussions, as well as adapted from existing parent feeding practice measures. Cognitive interviews were conducted with 37 adults to evaluate items. In the quantitative phase, mothers and fathers of 174 Mexican American children ages 8–10 completed the PFP and provided demographic information. Anthropometric measures were obtained on family members. Results: Confirmatory factor analyses identified four parental feeding practice dimensions: positive involvement in child eating, pressure to eat, use of food to control behavior, and restriction of amount of food. Factorial invariance modeling suggested equivalent factor meaning and item response scaling across mothers and fathers. Mothers and fathers differed somewhat in their use of feeding practices. All four feeding practices were related to child body mass index (BMI) percentiles, for one or both parents. Mothers reporting more positive involvement had children with lower BMI percentiles. Parents using more pressure to eat had children with lower BMI percentiles, while parents using more restriction had children with higher BMI percentiles. Fathers using food to control behavior had children with lower BMI percentiles. Conclusions: Results indicate good initial validity and reliability for the PFP. It can be used to increase understanding of parental feeding practices, children’s eating, and obesity among Mexican Americans, a population at high risk of obesity

Parental feeding practices and child weight status in Mexican American families: a longitudinal analysis

Parental feeding practices are thought to influence children\u27s weight status, through children\u27s eating behavior and nutritional intake. However, because most studies have been cross-sectional, the direction of influence is unclear. Moreover, although obesity rates are high among Latino children, few studies of parental feeding practices have focused on this population. This 2-year longitudinal study examined mutual influences over time between parental feeding practices and children\u27s weight status, in Mexican American families with children 18 years old at baseline. Mothers (n = 322) and fathers (n = 182) reported on their feeding practices at baseline, 1-year follow-up, and 2-year follow-up. Weight status, defined by waist-height ratio (WHtR) and body mass index (BMI), was ascertained at all assessments. Cross-lagged panel models were used to examine the mutual influences of parental feeding practices and child weight status over time, controlling for covariates. Both mothers\u27 and fathers\u27 restriction of food predicted higher subsequent child weight status at Year 1, and for fathers this effect was also found at Year 2. Mothers\u27 and fathers\u27 pressure to eat predicted lower weight status among boys, but not girls, at Year 1. Child weight status also predicted some parental feeding practices: boys\u27 heavier weight predicted mothers\u27 less pressure to eat at Year 1, less use of food to control behavior at Year 2, and greater restriction at Year 2; and girls\u27 heavier weight at Year 1 predicted fathers\u27 less pressure to eat and less positive involvement in child eating at Year 2. This study provides longitudinal evidence that some parental feeding practices influence Mexican American children\u27s weight status, and that children\u27s weight status also influences some parental feeding practices. Feeding practices of both mothers and fathers were related to children\u27s weight status, underscoring the importance of including fathers in research on parental feeding practices and child obesity

Longitudinal Effects of Parental, Child and Neighborhood Factors on Moderate-Vigorous Physical Activity and Sedentary Time in Latino Children

Background: Moderate-vigorous physical activity (%MVPA) confers beneficial effects on child musculoskeletal health, cardiovascular fitness, and psychosocial well-being; in contrast, sedentary time (%SED) is emerging as a risk factor for health. This study aimed to identify parental, child and neighborhood factors influencing longitudinal assessments of body mass index (BMI) and activity patterns among Latino children, and to estimate lagged and cross-lagged effects between child BMI, %MVPA and %SED. Methods: A longitudinal design with assessments at baseline, 1 and 2 years follow-up (FU) was used to evaluate the effects of maternal and paternal factors (BMI, age, education level, acculturation, household income and household size), child factors (gender, age, BMI, pubertal status) and neighborhood factors (disorder, victimization) on child BMI, %MVPA and %SED, expressed as a percent of awake time, in 282 Latino children ages 8–10 y and their parents. This study was restricted to families with a mother and biological father or father figure in the child’s life. Results: Across time, total daily accelerometer counts (p = 0.04) and steps decreased (p = 0.0001), %SED increased (p = 0.0001), and %MVPA decreased (p = 0.02). Moderate lagged effects or tracking was seen for %MVPA and %SED (p = 0.001). %MVPA varied by gender (5.5% higher in boys than girls, p = 0.0001); child age (−0.4% per year, p = 0.03), and child BMI in boys only (−0.22%, p = 0.0002). Negative effects of paternal age, maternal education and maternal changes in BMI on %MVPA also were seen. %SED increased with child age (2.5% higher per year, p = 0.0001). Positive effects of paternal acculturation, maternal change in BMI, paternal age, and negative effects of household size on %SED were observed. A cross-lagged positive effect of BMI at FU1 on %SED at FU2 was observed for boys and girls (p = 0.03). Neighborhood disorder and victimization were not significant predictors of child BMI, %MVPA or %SED. Conclusion: The major child determinants of physical activity (age, gender and BMI) and minor parental influences (maternal BMI and education, paternal age and acculturation) should be considered in designing interventions to promote %MVPA and reduce %SED among Latino children as they approach adolescence. Keywords: Physical activity patterns, Accelerometers, Childhood obesity, Maternal factors, Paternal factors, Education level, Acculturation, Household income, Household size, Environment, Disorder, Victimizatio