Journal Article•
Tincalconite Crystals from Searles Lake, San Bernardino County, California
TL;DR: It was pointed out by Schallera that Shepard's tincalconite was the S-hydrate of the borax series, NazO 2BzOt..
Abstract: This appeared in a section of the Bulletin headed \"Extraits de diverses publications.\" Literature references are given for most of the extracts, all of which are concerned with new mineral names, but no reference si given with the extract on tincalconite which is quoted in full above. No trace has been found of any original publication by Shepard2 on this material and it seems that such may never have been accomplished. Mineralogists generally3 considered the name tincalconite to apply to a variety of borax rather than to a distinct mineral. After half a century it was pointed out by Schallera that \"it is obvious\" that Shepard's tincalconite \"was the S-hydrate of the borax series, NazO 2BzOt.5HzO identical in composition with 'octahedral borax'.\" According to Schaller it is \"not very abundant but rather widespread, coating both borax and kernite.\" It forms from borax, the 10 hydrate of the series, by partial dehydration or from kernite, the 4 hydrate, by hydration. So far it has been found only in powdery form. Natural borax crystals such as are found embedded in the muds of Borax Lake in Lake County and Searles Lake in San Bernardino County, California, and numerous other localities are probably partly or wholly altered to the S-hydrate and so should be considered pseudomorphs of tincalconite after borax. It is very easy to observe the process of partial
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TL;DR: Krivovichev et al. as discussed by the authors analyzed structural complexity with the program package TOPOS, using complexity parameters that provide Shannon information content per atom and per unit cell (hereafter noted simply as “bits”).
Abstract: Boron minerals are among the most structurally and chemically complex naturally occurring inorganic compounds. Of the 291 B minerals recognized as valid or potentially valid, structures are known for 256 species (plus three polytypes); for 245 of these the age of the earliest reported occurrence in the geologic record has also been reported. The earliest B minerals are four tourmaline species formed during metamorphism at 3550 Ma in the Isua supracrustal belt (Greenland), but many ephemeral B minerals are restricted to Late Cenozoic and Holocene deposits. We analyzed structural complexity with the program package TOPOS, using complexity parameters that provide Shannon information content per atom and per unit cell (Krivovichev 2013). The average content per unit cell, 343 bits/unit cell (hereafter noted simply as “bits”), is significantly greater than the mode complexity ( ca . 175 bits) because distribution of complexity is strongly right-skewed. Qingsongite, cubic BN (2 bits), is the simplest boron mineral. Seventeen B minerals possess information content per unit cell > 1000 bits. Rogermitchellite, Na 6 (Sr,Na) 12 Ba 2 Zr 13 Si 39 (B,Si) 6 O 123 (OH) 12 ·9H 2 O, which is the most complex (2321 bits), owes its structural complexity in part to the incorporation of eight essential chemical elements. However, chemically simpler hydrated Ca borates (with four or five essential elements), e.g ., ginorite, Ca 2 B 14 O 20 (OH) 6 ·5H 2 O (1506 bits); ruitenbergite, Ca 9 B 26 O 34 (OH) 24 Cl 4 ·13H 2 O (1492 bits); and alfredstelznerite, Ca 4 B 16 O 16 (OH) 24 ·19H 2 O (1359 bits), are also structurally complex, which we attribute to the interplay of borate polyanions and hydrogen bonding networks. The earliest complex borates are takeuchiite (1179 bits), blatterite (1656 bits), and the Mg analogue of blatterite (1612 bits), which are reported uniquely from 1825 Ma deposits at Langban and Nordmark (Sweden). There is little evidence for a significant increase in maximum structural complexity since 1825 Ma. Localities with high boron mineral diversity (nine to 25 species) are more likely to contain minerals with complex structures, which could be simply a matter of there being more minerals present, which increases the chance that one of these minerals would be structurally complex. The variation of structural complexity with time shows features of a “passive” trend in mineral evolution – more minerals with complex structures arise with the passage of geologic time, yet the simpler structures are not supplanted; instead, new simpler structures also appear, e.g ., tourmaline-supergroup minerals (176 to 207 bits).
51 citations
TL;DR: In this article, Gibbs free energy-composition diagrams based on known solubility-temperature relations in the systems Na2B4O7-H2O and Na2b4O-7-NaCl-H 2O, are used for the interpretation and prediction of the stability relations in these systems; in particular these diagrams indicate clearly that tincalconite is everywhere a metastable phase.
33 citations
TL;DR: In this article, a petrologic study of core samples from two exploratory wells in the Doganlar sector, under optic and electron microscopy, reveals a complex mineral association in which probertite, glauberite, and halite constitute the major primary phases (without mineral precursors) precipitated in a saline lake placed in a volcano-sedimentary context.
28 citations
TL;DR: In this article, the quadrupole splittings of the B11 nuclear magnetic resonance (NMR) signals in single crystals of borax, Na2B4O7·10H2O, and tincalconite were investigated.
Abstract: The quadrupolar splittings of the B11 nuclear magnetic resonance (NMR) signals in single crystals of borax, Na2B4O7·10H2O, and tincalconite, Na2B4O7·5H2O, have been investigated. The electric quadrupole coupling constants, eqQ/h, and asymmetry parameters η of the electric field gradient tensors at the two unique B11 sites in the two crystals were determined to be BoraxTincalconiteeqQ/h487±1 kc/sec2544±4 kc/sec478±1 kc/sec2528±3 kc/secη0.714±0.0030.089±0.0150.473±0.0050.039±0.017. The orientations of the principal axes of the electric field gradient tensors for the above sites and their symmetry‐related sites have also been determined.The picture of the boron—oxygen polyion in borax as given by NMR is in complete agreement with the x‐ray results as to numbers and coordinations of boron atoms, symmetry of the polyion and orientation of the planes of the triangularly coordinated boron atoms. The NMR results also indicate that the same boron—oxygen polyion occurs in tincalconite as in borax.
18 citations
TL;DR: In this paper, the influence of borax on the crystallization kinetics of sodium sulfate was studied under controlled environmental conditions, which was carried out in mixtures in glass microcapillaries, and sequentially in droplets on glass plates.
Abstract: Borax has been identified as a possible crystallization modifier for sodium sulfate. Understanding the effect of borax on factors influencing transport and crystallization kinetics of sodium sulfate helps to clarify how this modifier might limit crystallization damage. It has been observed that the addition of borax to sodium sulfate solutions has no influence on the wetting properties (contact angle on glass, surface tension, or evaporation rate) and therefore will not influence solution transport. Additionally, the influence of borax on the crystallization kinetics of sodium sulfate was studied under controlled environmental conditions. This was carried out in mixtures in glass microcapillaries, and sequentially in droplets on glass plates. Under the here studied precipitation conditions, the addition of borax has no influence on the supersaturation ratio at the onset of crystallization, but it significantly affects the crystallization pattern of anhydrous sodium sulfate crystals (thenardite). Using RAMAN spectroscopy, two different hydrates of borax were identified after precipitation, depending on the initial concentration of the solution. Each hydrate has a different effect on the subsequent crystallization of sodium sulfate. The decahydrate polymorph of borax leads to the precipitation of hydrated sodium sulfate crystals (mirabilite) and the pentahydrate form favors the precipitation of the anhydrous sodium sulfate crystals (thenardite) with an altered crystal habit. Using X-ray diffraction, overdevelopment of the (111), (131), (222) and (153) faces of thenardite was identified. Additionally, the ratios between several peaks are reversed. These results confirm the deviation of the grown crystals of the equilibrium crystal shape of thenardite as observed with optical microscopy.
17 citations
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01 Jan 1930
TL;DR: The first sample of these borate minerals was received by the writer f"om Hoyt S. Gale, of Los Angeles, in the fall of 1926 as mentioned in this paper, which forms the basis of this report.
Abstract: The development of the borate deposits of the Kramer dis trict, in the Mohave Desert, Calif., received a strong impulse in 1926 by the discovery there of'a large deposit of the new sodium borate, kernite. This deposit lies about 2~ miles east of the original discovery of colemanite and ulexite in the Suckow shaft. All the borates occur underground, there being no indicu.tion whatever at the surface of the existence of any borates below. The original discovery was made in drilling for water. The first sample of these borate minerals was received by the writer f"om Hoyt S. Gale, of Los Angeles, in the fall of 1926. In September, 1927, through the courtesy of Mr. Clarence M. Rasor, of the Pacific Coast Borax Co., an opportunity was had to visit the kernite deposit and collect material, which forms the basis of this report. The kindness of Mr. Rasor in allowing the collection and study of material is much appreciated. The geologic setting of the kernite deposit is imperfectly known, but in general it is similar to that of the deposits a few miles west which have been described by Noble. The borate minerals, several hundred feet underground, occur in a complex clay series and are underlain by igneous rock, whether extrusive (and therefore of earlier age than the borates) or intrusive (and therefore of later age than the borates) is not known. Knowl edge of this relative age of the lava would be of great help in understanding the genesis of the borate minerals. The borate minerals found inolude colemanite, ulexite, borax, tincalconite, and two new borates, kernite and kramerite. The u.ssociated minerals are calcite, realgar, stibnite, and the clay minerals. Kernite was briefly described in a preliminary paper in JanuH.ry, 1927; kramm'ite is first described in this paper. Abundant and better material, recently collected by the writer, has fumished the basis for fuller description of kemite and also shows that some of the statements made in the original brief paper need to be corrected. The composition of the two new minerals is as follows: Kernite, Na20.2B20a.4H20. Kramerite, Na20.2CaO.5B20a.10H20. Kernite occ'uI"s in greater quantity and is Of greater interest scientifically. It is the commercial mineral mined, existing as an immense deposit a hundred feet thick and many hundred feet in lateral extent. The deposit contains an estimated minimum of well over a million tons. Some. of the crystals are of immense size, the largest one seen measuri.ng 8 feet in thick ness. Many of the crystals are several feet across. The mineral belongs chemically to the borax group but has only 4 molecules of water instead of 10, as in borax. The crystals are monoclinic, with the axial ratio a : b : c= 1.5230 : 1 : 1.6989, {:J =71 0 08'. Thirty-six crystal forms were observed, together with' many additional vicinal forms. Two. perfect cleavages break the mineral up into elongated rhombic prisms. Kramerite occurs in small quantities as radiating prisms, averaging not over a millimeter in thickness. It is monoclinic, with the axial ratio a: b: c=1.1051: 1: 0.5237, {3=72° 16'. Eight crystal forms were identified. In composition, krameritc, is like ulexite but with less water. It was probably artificially made by Van't Hoff. The prisms of kramerite cut the clay, kernite, and borax and are of later origin. Tincalconite, Na20.2B20a.5H20, named by Shephard in 18781 is, as found, always secondary, forming by dehydration of borax and by hydration of -kernite. It is a finely, crystalline aggregate, existing only as a coating on the other borates. These three sodium borates have been made artificially in the chemical laboratory of the Geological Survey in Wash ington. A comparison of the properties of a number of hydrates in the different series-the borax series, the colemanite series has been made. The origin of the deposit forms a separate problem in which the mineral relationships are the chief criteria. The geologic relations are so little known in detail that the processes of formation can only be suggested at this time. The kernite was perhaps formed by the fusion in its own water of crystalliza tion of a previous accumulation of borax crystals, enough water being driven off to yield on solidification of the fused borax the 4-hydrate kernite. If no water could escape the resultant product was massive borax. A list of all known boron minerals is added, with some critical remarks about their relationship and standing. A bibliography of the borate minerals of the Kramer district ends the paper. LOCALITY
10 citations