NEW UNIT LAYERS FOR MICAS

HIROSHI TAKEDA; RYOICHI SADANAGA

doi:10.2465/minerj1953.5.434

HIROSHI TAKEDA, RYOICHI SADANAGA

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JOURNAL FREE ACCESS

1969 Volume 5 Issue 6 Pages 434-449

DOI https://doi.org/10.2465/minerj1953.5.434

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Published: 1969 Received: December 14, 1968 Available on J-STAGE: March 18, 2008 Accepted: - Advance online publication: - Revised: -
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Date of correction: March 18, 2008 Reason for correction: - Correction: ABSTRACT Details: Wrong : A new choice of unit layer proposed by Sadanaga & Takeda (1968) has been found useful for explaining the two characteristic features of the X-ray diffraction pattern of the mica, namely, the periodic intensity distribution and the partial enhancement of symmetry. The recognition of the fact that the symmetry of the new unit layers is higher than that of the crystal, played an important role in the derivation of intensity distribution functions.
By the introduction of four kinds of layer with either trigonal or hexagonal symmetry and designated D, D^*, T and T^*, the layer sequence of any mica polytype can be described by stacking of these layers in parallel orientation and with mutual staggers of 1/3._a₁, 1/3._a₂ and 1/3._a₃. With the aid of these new unit layers, it is proposed a new symbol to describe the stacking sequence of mica, together with a convention of axial settings to specify the symbol uniquely.
Right : A new choice of unit layer proposed by Sadanaga & Takeda (1968) has been found useful for explaining the two characteristic features of the X-ray diffraction pattern of the mica, namely, the periodic intensity distribution and the partial enhancement of symmetry. The recognition of the fact that the symmetry of the new unit layers is higher than that of the crystal, played an important role in the derivation of intensity distribution functions.
By the introduction of four kinds of layer with either trigonal or hexagonal symmetry and designated D, D^*, T and T^*, the layer sequence of any mica polytype can be described by stacking of these layers in parallel orientation and with mutual staggers of 1/3·a₁, 1/3·a₂ and 1/3·a₃. With the aid of these new unit layers, it is proposed a new symbol to describe the stacking sequence of mica, together with a convention of axial settings to specify the symbol uniquely.

Date of correction: March 18, 2008 Reason for correction: - Correction: PDF FILE Details: -

Abstract

A new choice of unit layer proposed by Sadanaga & Takeda (1968) has been found useful for explaining the two characteristic features of the X-ray diffraction pattern of the mica, namely, the periodic intensity distribution and the partial enhancement of symmetry. The recognition of the fact that the symmetry of the new unit layers is higher than that of the crystal, played an important role in the derivation of intensity distribution functions.
By the introduction of four kinds of layer with either trigonal or hexagonal symmetry and designated D, D^*, T and T^*, the layer sequence of any mica polytype can be described by stacking of these layers in parallel orientation and with mutual staggers of 1/3·a₁, 1/3·a₂ and 1/3·a₃. With the aid of these new unit layers, it is proposed a new symbol to describe the stacking sequence of mica, together with a convention of axial settings to specify the symbol uniquely.

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