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IS0
I N TE R N AT1 O N AL O R GAN I2 AT1 O N F O R STAN DAR D I Z AT I O N
IS0 RECOMMENDATION
R 444
PHLOGOPITE MICA
BLOCKS, THINS AND SPLITTINGS
METHOD FOR GRADING BY SIZE
1st EDITION
September 1965
COPYRIGHT RESERVED
The copyright of IS0 Recommendations and IS0 Standards
belongs to IS0 Member Bodies. Reproduction of these
documents, in any country, may be authorized therefore only
by the national standards organization of that country, being
a member of ISO.
For each individual country the only valid standard is the national standard of that country.
Printed in Switzerland
Also issued in French and Russian. Copies to be obtained through the national standards organizations.
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BRIEF HISTORY
The IS0 Recommendation R 444, Phlogopite Mica Blocks, Thins and Splittings. Method
for Grading by Size, was drawn up by Technical Committee ISO/TC 56, Mica, the Secretariat
of which is held by the Indian Standards Institution (ISI).
Work on this question by the Technical Committee began in 1950 and led, in 1961, to
the adoption of a Draft IS0 Recommendation.
In August 1963, this Draft IS0 Recommendation (No. 598) was circulated to all the IS0
Member Bodies for enquiry. It was approved by the following Member Bodies :
Argentina France Portugal
Australia India United Kingdom
Brazil Japan U.S.S.R.
Chile Korea, Rep. of
Czechoslovakia Netherlands
No Member Body opposed the approval of the Draft.
The Draft IS0 Recommendation was then submitted by correspondence to the IS0
Council, which decided, in September 1965, to accept it as an IS0 RECOMMENDATION.
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ISOlR 444 - lM5(E)
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CONTENTS
Page
Foreword . 3
1.Scope . 4
2. Terminology . 4
3. Grading method . 5
3.1 Principle . 5
3.2 Grade designations . 5
3.3 Sequence of operations . 5
4. Trimming. . 5
4.1 Full-trimmed mica . 5
4.2 Partially-trimmed mica . 5
4.3 «V»cuts . 5
5. Grading procedure and measurement of thickness . 5
5.1 Grading chart . 5
5.2 Grading procedure . 7
5.3 Measurement of thickness . 7
6. Tolerance. . 7
Table. - Standard grading table for phlogopite mica blocks, thins and splittings . 6
Grading chart for phlogopite mica blocks, thins and splittings . 8
FOREWORD
I. This IS0 Recommendation deals with size grading of phlogopite mica and does not cover
classification according to behaviour under heat, which will be the subject matter of a separate
IS0 Recommendation.
II. In one important respect, there is similarity between this IS0 Recommendation and that for
grading of muscovite mica. The grading scale prescribed hereafter is the same as that which
applies to muscovite blocks and thins. * The designations proposed for grading are based
on preferred numbers of series R 20, in accordance with IS0 Recommendation R 3, Pre-
- Series of Preferred Numbers.
ferred Numbers
III. The commercial forms of phlogopite mica, namely, blocks, thins and splittings, are cut or
trimmed (fully or partially, depending on the purpose of use) with knife or sickle before sale.
* See IS0 Recommendation R 67, Muscovite Mica Blocks, Thins and Films. Methods for grading by size.
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F
ISOlR 444 - 1965 (E)
~
IS0 Recommendation R 444
September 1965
PHLOGOPITE MICA
BLOCKS, THINS AND SPLITTINGS
METHOD FOR GRADING BY SIZE
1. SCOPE
This IS0 Recommendation describes a standard method for grading phlogopite mica blocks,
thins and splittings, according to size, and includes trimming requirements and definitions of
relevant terms used in the trade.
2. TERMINOLOGY
For the purposes of this IS0 Recommendation, the following definitions apply :
2.1 Crude mica. Crude crystals or books, as extracted from the mine.
2.2 Cobbing. The Process of removing dirt and rock from crude mica.
2.3 Rifting. The Process of splitting cobbed mica into sheets of suitable thicknesses.
2.4 Trimming or dressing. The Process of removing major flaws from rifted mica. Trimming may
be accomplished with sickle or knife and the mica is then named after the implement used,
sickle-trimmed mica or knife-trimmed mica.
2.5 Sickle-trimmedmica. Crude mica cobbed, rifted and trimmed with a sickle to eliminate major
flaws, and left with irregular outline and bevelled edge.
2.6 Knife-trimmed mica. Sickle-trimmed mica, further refined with a knife to eliminate interior
defects and also such defects as may have been overlooked by the sickle-cutter.
2.7 Commercial forms of mica. Mica known as blocks, thins and splittings.
2.8 Blocks. Knife-trimmed mica of a specified minimum thickness, which may be, with a maximum
tolerance of 5 per cent (by mass),
either 0.20 mm (0.008 in) with a tolerance limit at 0.18 mm (0.007 in),
or 0.18 mm (0.007 in) with a tolerance limit at 0.15 mm (0.006 in),
as agreed between the buyer and the seller.
2.9 Thins. Knife-trimmed mica in any specified thickness between 0.05 mm (0.002 in) and O. 18 mm
(0.007 in).
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