Classification of borate minerals

Strunz, H.

doi:10.1127/ejm/9/1/0225

Cited by 49 publications

(24 citation statements)

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“…The intrinsic symmetry of the macallisterite block, denoted as -PO, corresponds to point group 3 m, but its local pseudosymmetry does not correspond to the symmetry of the structure. Another variation of the hexaborate block is characteristic of boracites (figure 1c), which are classified by Strunz [2] with heptaborates, section 6.GA. The topology of this block is identical to the macallisterite block with the terminal BO 3 triangles replaced by BO 4 tetrahedra: its formula is 6[6T].…”

Section: Hexaboratesmentioning

confidence: 99%

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Borate crystal chemistry in terms of the extended OD theory: topology and symmetry analysis

Белоконева

2005

Crystallography Reviews

127

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Section: Hexaboratesmentioning

confidence: 99%

“…A block in the OD theory is the same as the FBB in borate systems [2,3]. However, the use of topological analysis (with some units distinguished) in tandem with symmetry analysis of OD-theory enables one to find the crystal chemical peculiarities, to position a compound in the system more correctly and to predict hypothetical structures.…”

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confidence: 99%

Borate crystal chemistry in terms of the extended OD theory: topology and symmetry analysis

Белоконева

2005

Crystallography Reviews

127

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“…On the basis of the results of our research, olshanskyite is a neso-triborate (Strunz 1997), and its crystal structure is based on finite borate clusters (FBB = 3Ⅺ, Hawthorne et al 1996). …”

Section: Discussionmentioning

confidence: 99%

“…They provided confirmation of the ideal formula unit Ca 3 B 4 (OH) 18 given by Bogomolov et al (1969) and established the triclinic unit-cell: a 9.991, b 14.740, c 7.975 Å, ␣ 94.53°, ␤ 69.08°, ␥ 112.44°, Z = 3. Strunz (1997) classified olshanskyite among nesoborates containing H 2 O molecules or additional OH anions.…”

Section: Introductionmentioning

confidence: 99%

The Crystal Structure of Olshanskyite

Callegari

Mazzi

Tadini

2001

The Canadian Mineralogist

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X-ray intensity data for olshanskyite, Ca 2 [B 3 O 3 (OH) 6 ]OH•3H 2 O, were collected from a crystal from the Fuka mine, Okayama Prefecture, Japan, using a PW1100 Philips single-crystal diffractometer. Olshanskyite is triclinic, a 7.953(4), b 9.873(9), c 7.362 (6) Å, ␣ 111.00(7), ␤ 94.65(7), ␥ 107.53(7)°, space group P1, Z = 2. The crystal structure was solved and refined to R = 0.017 for 3833 observed reflections and to R = 0.022 for all unique reflections (4419). The anionic group in the structure is a threemembered ring of boron-oxygen tetrahedra [B 3 O 3 (OH) 6 ] 3-. Two independent calcium atoms occur in a distorted square-antiprism coordination with five oxygen atoms from the borate group and three hydroxyl or H 2 O groups external to the borate cluster. The apparent discrepancies between the unit-cell parameters and the formula unit of olshanskyite resulting from the present research and those previously determined are attributed to two alternative interpretations of the same chemical and X-ray powder data. Analogies and differences between the crystal structure of olshanskyite and that of the analogous borate nifontovite Ca 3 [B 3 O 3 (OH) 6 ] 2 •2H 2 O also are discussed. Olshanskyite must be classified as a neso-triborate, and its structure is based on finite borate clusters (FBB = 3Ⅺ).

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“…Such a layer was never found in borates before. Anionic layer radical is composed of tetrahedrons (T) and triangles (D) without forming special borate fundamental building blocks, so new borates should be classified as polyborates of two types simplest blocks [10,11]. Crystal chemical formula of new layer is ½B 6 O 10 ðOHÞ 2 4À ∞∞ because B2-triangles occupy statistically only two positions attributable to the four tetrahedrons, notation is 6:[4T þ 2D] ∞∞ , or three on a ring of six tetrahedrons, [6T þ 3D] ∞∞ (Fig.…”

Section: Structuresmentioning

confidence: 99%