Mineral Grain–Complete - · PDF file1 The Mineral Grain and Mineral-grain Surfaces: a...
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The Mineral Grain
and Mineral-grain
Surfaces:
a low-technology
approach, description,
and use
By Wallace D. Kleck NoticeI claim copyright protections for this work and its contents. However, I freely
grant anyone permission to make one paper or electronic copy for their own personal use. If any
of the contents are quoted, there must be an appropriate technical reference. The total or any part
of this work, may not be copied for sale or sold without the direct, personal permission of
Wallace D. Kleck or his estate. I may be contacted by standard-mail at 23940 Basin Harbor Court, Tehachapi, CA, 93561 or by e-mail at [email protected].
So stated, May, 10, 2012, Tehachapi, California.
mailto:[email protected]
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TABLE OF CONTENTS
Note, page numbers are shown for 1st and 2
nd
level headings
------section heading---------------------------------------------------------------------page
ABSTRACT 1
INTRODUCTION 1
DEFINITIONS 2
FORMATION OF GRAINS 4
GRAIN SURFACESPROCESSES OF FORMATION 5
Grain Growth 5
Growth-free
Growth-partially-free
Growth-restricted
Dissolution (s.l.--sensu lato) 6
Mechanical Modification 6
Other (Grains at or Near Equilibrium) 6
MINERAL GRAIN AND CRYSTAL 7
MINERALOID 8
GRAIN SURFACESDETAILS 8
Growth Surfaces (redefined; new) 9
Type-1 surfaces
Type-2 surfaces
Type-3 surfaces
Type-4 surfaces
Type 4-1 surfaces; mutual growth and relative bond strength
Type 4-1 surfaces; metamorphic environments
Type 4-1 surfaces; igneous environments
Type-5 surfaces
Paramorphic-surfaces (redefined) 22
Dissolution (s.l.) (modified) 23
Features of melt surfaces
Features of a chemical solution surface
Features of dissolution surfaces on quartz phenocrysts in rhyolite
Recognizing dissolution surfaces
Mechanically modified (new) 28
Phantom Surface (modified) 30
Artificial 30
Mineraloid (modified) 30
Gel-mineral (modified)
Grain-replaced (new)
Crystallized gel (new)
Grain-metamict.
Grain-domain Containing (new)
THREE EXAMPLES 34
Pegmatite-Example 1 34
Quartz in Rhyolite (Crystal Tuff)-Example 2 35
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Spodumene Crystal-Example 3 36
DISCUSSION 36
Other Surfaces 36
Crystals 37
Mixed and Complex Surfaces 37
Surfaces on Grains from Pegmatite Rocks 37
Grains in Cavities36
Some Comments on the Nature of Selected Minerals 42
Feldspar (in crystal tuffs)
-quartz (in crystal tuffs)
Mica (in a variety of environments)
Graphite (in tactite)
CREATION OF SUITABLE GRAINS FOR STUDY 43
Weathering 43
Cavities 44
Artificially Crushed, Broken, or Naturally Fragmented Rocks 44
Separation by Chemical or Physical Properties 44
ACKNOWLEDGEMENTS 44
REFERENCES CITED 45
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The Mineral Grain and Mineral-grain Surfaces: a low-technology approach and uses
Wallace D. Kleck [email protected]
23940 Basin Harbor Court, Tehachapi, California 93561, USA; retired--no present college
affiliation
ABSTRACT
A grain (mineral grain) is redefined as the fundamental unit of mineralogy. Grain surfaces (in
3-dimensions) provide considerably more information about the geologic history of grains in a
rock than do a small number of thin sections through grains. Grain surfaces are formed by one or
a combination of growth, dissolution, and mechanical modification. Herein, grain surfaces are
divided into six classes and ten subclasses (in parentheses)growth (type-1, type-2, type-3,
type-4, type 4-1, type-5), paramorphic, dissolution, mechanically modified (cleavage, parting,
fracture, smoothed), phantom, and artificial. In addition, mineraloid is redefined and divided into
five subclasses (gel-mineral, grain-replaced, crystallized gel, grain-metamict, and grain-domain
containing).
Type 4-1 growth surfaces are a newly defined type of surface, resulting from competitive growth
(primarily) in igneous and metamorphic environments. It is proposed that the determining factor
in the goodness of development of crystal surfaces on such grains is the relative difference in
bond strength. An imprecise measure of the difference in bond strength is the relative difference
in mineral hardness (H). Where the difference of hardness between two competing grains is
approximately >2, recognizable crystal surfaces develop.
INTRODUCTION
For approximately 100 years, petrologists and mineralogists have dealt with the interpretation of
the features of mineral grains primarily in section. This is a useful and well developed technique,
but it ignores features that can provide a great deal of information about the environment of
formation of mineral grainsi.e. the nature of and the features on the surfaces of the mineral
grains. These surface features are the last to form and then are the latest of the mineral-grain
surface features. For a compete interpretation of the grains, this information needs to be added to
information about the internal (and former grain surfaces) features gained by section studies.
This paper has three purposes:
To gather and develop information on the origin and nature of grain surfaces;
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To develop a classification system that places this information in a coordinated and logical format;
To demonstrate how this information can be used. In doing this, it is necessary to develop a certain amount of new terminology and to modify some
existing terminology; if this approach is valid, the new and modified terminology will need to
become a part of mineralogy and petrology. It is suggested that information on grain surfaces
become one of the standard types of information collected and interpreted for mineral grains in
rocks.
Further, this paper is primarily concerned with natural, solid grains that have formed at or near
the surface of Earth. It is not that other substances or environments are uncommon or
uninteresting, but for the practical reasons of length and coherence of topic. The surface and near
surface processes of the planetary body called Earth are complex enough. But as we scientists
begin to consider the interior of Earth, outer-space, other planetary bodies, etc., the job of
understanding natural solids grows to unimagined proportions. Truly, we are cursed (or blessed)
and live in interesting times.
Note that Geosphere (the GSA online jo