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Abstract


Volume: 31 (1947)

Issue: 8. (August)

First Page: 1479

Last Page: 1490

Title: Terminology for Insoluble Residues

Author(s): H. A. Ireland (2)

Abstract:

The rapid development of the use of insoluble residues for correlation since 1940 has resulted in a diverse terminology which needs standardization. A group of geologists familiar with residue work agreed in conference upon terminology and definitions, and developed the outline included in this article. The contents of the outline are based on description rather than on genesis, since the genesis of many constituents of residues is not known or is controversial. The outline and its contents are submitted as a guide to new workers and as a common source of agreement among those most familiar with correlation and identification using insoluble residues. The term insoluble residues is herein restricted to the residues from digestion in dilute hydrochloric acid.

Text:

The publication of H. S. McQueen in 1931 (FOOTNOTE 4) established methods of preparation, terminology, and practical application of insoluble residues for subsurface and surface correlation and identification of calcareous rocks. Nearly all subsequent workers during the following 10 years visited Rolla, Missouri, for introduction to McQueen's methods and procedure. Early work prior to 1938 applying residue examination to subsurface geology was done by Littlefield,(FOOTNOTE 5) Hiestand (FOOTNOTE 6) and Ockerman (FOOTNOTE 7) in Kansas, Ireland (FOOTNOTE 8) in Oklahoma, and Burpee and Wilgus (FOOTNOTE 9 ) in New Mexico. Early workers on residues from surface beds were Ireland,(FOOTNOTE 10) Martin (FOOTNOTE 11) and Merritt.(FOOTNOTE 12)

FOOTNOTE 4. H. S. McQueen, "Insoluble Residues as a Guide to Stratigraphic Study," Missouri Bur. Geol. and Mines 56th Bien. Rept. (1931). Appendix I, 32 pp.

FOOTNOTE 5. Max Littlefield, Gulf Oil Corporation. (Unpublished work.)

FOOTNOTE 6. T. C. Hiestand, "Studies of Insoluble Residues from 'Mississippi Lime' of Central Kansas," Bull. Amer. Assoc. Petrol. Geol., Vol. 22 (1938), pp. 1588-99.

FOOTNOTE 7. J. W. Ockerman, "Insoluble Residues of the Hunton and Viola Limestones of Kansas," Jour. Sed. Petrol., Vol. 1 (1931), pp. 43-46.

FOOTNOTE 8. H. A. Ireland, "Use of Insoluble Residues for Correlation in Oklahoma," Bull. Amer. Assoc. Petrol. Geol., Vol. 20 (1936), pp. 1086-1121.

FOOTNOTE 9. G. E. Burpee and W. L. Wilgus, "Insoluble Residue Methods and Their Application to Oil Exploitation Problems," Mining and Metallurgy, Vol. 16 (1935), pp. 418-20.

FOOTNOTE 10. H. A. Ireland, op. cit.

FOOTNOTE 11. H. G. Martin, "Insoluble Residue Studies of Missippian Limestones in Indiana," Indiana Dept. Conserv. Pub. 101 (1931), 37 pp.

H. G. Martin, "The Insoluble Residues of Some Mississippian Limestones of Western Kentucky," Kentucky Geol. Survey, Ser. 6, Vol. 41 (1931), pp. 129-89.

FOOTNOTE 12. C. A. Merritt and C. E. Decker, "Physical Characteristics of the Arbuckle Limestone," Oklahoma Geol. Survey Cir. 15 (1928). 54 pp.

End_Page 1479------------------------------

After 1938 many papers, reports, abstracts, and unpublished work on surface and subsurface studies indicate the increased interest and use of residues for correlation and identification of beds. The examination of residues for petroleum geology was not widely used until about 1940.(FOOTNOTE 13) By 1946 the State geological surveys of Illinois, Indiana, Kentucky, Tennessee, Missouri, Nebraska, Kansas, Oklahoma, and Texas had issued publications based wholly or in part on surface and subsurface data from insoluble residues. The United States Geological Survey recently issued three publications based on subsurface residue data.(FOOTNOTE 14) Most of the terminology for residues in Texas areas was developed independently of the usage of McQueen, partly because of needs for modification, an also because of independent thinking. Most of the usage has never been published and considerable diversity of nomenclature has developed.

The increase in the number of workers using residues resulted in a diversity of terminology in publications and unpublished practical usage. The table published by Cole (FOOTNOTE 15) is applied only to the Ellenburger formation of Texas but residue study may be applied to most of the calcareous formations of central United States. The terms are good but most of them are different from those used by workers outside Texas and the need for standardization is apparent. Terminology in future publications and usage of unpublished terms will undoubtedly increase and compound the diversity of descriptions and terminology for insoluble residues unless they are standardized. At the present time the technique is at a stage where standardization will not be difficult but diverse usage, especially unpublished usage, will make standardization more difficult as time progresses. Standardization is essential for the scientific and practical advancement of the use of residues.

In June, 1946, a 2-day conference was arranged in Midland, Texas, by H. A. Ireland for the purpose of standardizing the terminology used for insoluble residues. Geologists in the central United States who were active or known to be interested in residue work were invited. Special acknowledgment is due Leo Hendricks and W. A. Waldschmidt in developing the conference and in the work

FOOTNOTE 13. K. E. Born and H. B. Burwell, "Geology and Petroleum Resources of Clay County, Tennessee," Tennessee Dept. Conserv. Div. Geol. Bull. 47 (1939), pp. 20-57.

M. G. Cheney, "Geology of North-Central Texas," Bull. Amer. Assoc. Petrol. Geol., Vol. 24 (1940), pp. 65-118.

Leo Hendricks, "Subsurface Divisions of the Ellenburger in North-Central Texas," Univ. Texas Bur. Econ. Geol. Bull. 3945 (1940), pp. 923-68.

Taylor Cole, "Subsurface Study of Ellenburger Formation in West Texas," Bull. Amer. Assoc. Petrol. Geol., Vol. 26 (1942), pp. 1398-1409.

A. J. Crowley and Leo Hendricks, "Lower Ordovician and Upper Cambrian Subsurface Divisions in North-Central Texas," Bull. Amer. Assoc. Petrol. Geol., Vol. 29 (1945), pp. 413-25.

FOOTNOTE 14. H. A. Ireland, "Correlation and Subdivision of Subsurface Lower Ordovician and Upper Cambrian Rocks in Northeastern Oklahoma," U. S. Geol. Survey Chart 5, Oil and Gas Investig. Ser., with text (1944).

H. A. Ireland, "Maps of Northeastern Oklahoma and Parts of Adjacent States Showing the Thickness and Subsurface Distribution of Lower Ordovician and Upper Cambrian Rocks below the Simpson Group," U. S. Geological Survey Prelim. Map 52, Oil and Gas Investig. Ser., with text (1946).

A. J. Crowley and Leo Hendricks, op. cit. (released for outside publication).

FOOTNOTE 15. Taylor Cole, op. cit., pp. 1400-01.

End_Page 1480------------------------------

following the conference. Most of the participants brought slides of various types of residues labelled according to their own terminology. Residues were examined, discussed, and defined, and an organized outline was composed by those present. Those unable to attend were sent copies of the final results of the conference and after several revised editions the outline, definitions, and terminology published herein evolved. The definitions and terms published are not the opinion or usage of any one person. They are written word for word as agreed upon at the conference or as revised by a later conference and correspondence. It is hoped that the agreement by this group of active and experienced workers with insoluble residues will establish usage of the terminology and also serve new wor ers who may utilize insoluble residues as a means of correlation and identification.

Failure to use the terminology as established will destroy the value of the conference and again throw the study of residues into a chaos of diverse terms which will prevent progress and understanding. The reluctance of individuals to alter familiar and personal designations of terms will prevent the complete establishment of common terms judged preferable by those most qualified to judge. The conference was developed to forestall the vexing situation which has arisen in other fields where coordination and standardization were delayed until too late.

OUTLINE

The introduction to this article was written by the chairman of the conference, but the outline and definitions of terms are a collaboration of the participants of the conference. The writer assumes responsibility for introductory statements not part of the outline, and joint responsibility for the contents of the outline.

Terminology for the most part, follows the precedent of the Missouri Geological Survey, to which so much is owed for establishment of residues as a method. It is believed that their descriptions should be used as criterion because of the long usage and repeated appearance in the literature. Some modifications are made in the light of new knowledge and the experience of many workers. The significant changes are the use of the word "dolomoldic" for "dolocastic," "granular" for "crystalline"; "lacy" is restricted to fragments with irregular openings while "skeletal" is applied to fragments with rhombohedral openings.

The terminology is based on description rather than genesis of the residues because the genesis of many constituents is unknown, vague, or controversial. Residues are frequently called "siliceous residues," a designation which should be discarded. Many residues such as glauconite, pyrite, shale fragments, iron pellets, sphalerite, anhydrite, gypsum, and several other minerals are not siliceous.

The outline is organized according to the major constituents under headings of quartz, chert, argillaceous material, arenaceous material, anhydrite, gypsum, and accessory minerals and other constituents. A term is defined the first time it appears in the outline. The first-order headings are all nouns and the subheads are descriptive adjectives. Multiple subheads give additional specific and detailed

End_Page 1481------------------------------

description. Many possible types of residues are given a place in the outline, though their existence has not been confirmed. It is believed that the outline will contain a descriptive term for all anticipated types of residues, but it is recognized that additions or alterations may later be necessary.

As far as possible, each descriptive term is intended to be clear-cut and restrictive; and, within limits, a residue fragment may be pigeon-holed. It should be emphasized, however, that types of residues grade into other types and therefore some specific fragments may not be easily placed, and different persons may place a fragment under a different but related type.

The description of crystalline, quartzose, drusy, or granular siliceous material is greatly facilitated by separating quartz from chert and eliminating the terms vitreous and crystalline from the nomenclature. All clear, vitreous, and crystalline quartz is classified as euhedral, subhedral, or anhedral. Drusy quartz is specifically restricted to subhedral. The term "granular" is substituted for the term crystalline because the crystalline appearance of a fragment is generally due to the reflection of light from grains or granules. If a fragment is actually composed of recognizable quartz crystals it would be classified as some form of quartz thus preventing any confusion with a chert residue fragment. Much chert and other residues referred to as crystalline should be called "drusy." >

"Smooth" is a term applied to one of the three major types of chert. It is subdivided into chalcedonic, ordinary, and porcelaneous. "Chalcedonic" includes all vitreous, milky, translucent, and transparent chert. Other varieties of chert are described in the outline. Any of these cherts may be oolitic, dolomoldic, sandy, or otherwise modified as shown in the outline.

TERMINOLOGY FOR INSOLUBLE RESIDUES

I. QUARTZ: Ordinarily clear colorless quartz, not detrital
A. EUHEDRAL: Doubly terminated crystals; unattached
B. SUBHEDRAL: Crystal forms partially developed
1. Loose: Individual fragments separated from former attachment
2. Drusy: Clusters or aggregates of crystals; generally incrustations
3. Granulated: Grains or granules partially cemented or loosely aggregated; saccharoidal; grade from angular to drusy; fine to coarse; particle rarely larger than 0.5 mm. in diameter
a. Fine:
(1) Unmodified: Residue uniform with no modifying characteristics
(2) Lacy: Residues with irregular openings in which the constituent material comprises less than 25% of the volume of the fragment
(3) Drusy: Incrusted with subhedral quartz
(4) Dolomoldic: Containing dolomolds. (Dolomolds are rhombohedral openings in an insoluble residue. Term dolomoldic is used for same feature that McQueen originally called dolocastic.(FOOTNOTE 16) Term dolocastic is given by Cloud, Barnes, and Bridge (FOOTNOTE 17) to a feature not a dolomold and entirely different from original application by McQueen. Their definition of dolocastic should not be used because of confusion with original application by McQueen and widespread former usage of McQueen's term dolocastic in literature. See dolomorphic below.)
(a) Skeletal with dolomolds: Residues with rhombohedral openings in which constituent material comprises less than 25% of volume of fragment. Openings vary from microscopic to megascopic

FOOTNOTE 16. H. S. McQueen, op. cit. (1931) p. 9.

FOOTNOTE 17. P. E. Cloud, V. E. Barnes, and Josiah Bridge, "Stratigraphy of the Ellenburger Group in Central Texas--A Progress Report," Univ. Texas Pub. 4301 (1945), p. 135.

End_Page 1482------------------------------
(b) Abundant dolomolds: Residues with rhombohedral openings with constituent material comprising from 25% to 75% of the volume of fragment. Openings vary from microscopic to megascopic
(c) Scattered dolomolds: Residues having rhombohedral openings in which constituent material comprises more than 75% of volume of fragment. Openings vary from microscopic to megascopic
(5) Dolomorphic: Used for describing insoluble residues where there has been replacement or alteration of dolomite or calcite by insoluble mineral which assumes crystal form of the soluble mineral, thus filling a dolomoldic cavity. Term dolomorphic is same as dolocastic used by Cloud, Barnes, and Bridge. Dolomorphic describes conditions but does not put new meaning to obsolete word dolocastic
(6) Oolitic: Containing ooliths.(FOOTNOTE 18) (Ooliths as applied to insoluble residues are spheroidal bodies with nucleus or central mass enclosed by one or more surrounding layers of same or different material. Ooliths found as residues may be of any color. They may be composed of hematite, limonite, pyrite, bauxite, silica, clay, and barite. Any of these may have replaced dolomite, calcite, aragonite, siderite, or phosphate. Many ooliths differ in color and in composition from enclosing matrix. Ooliths grade from small to large but generally are less than 1.0 mm. in diameter. Those larger than 2.0 mm. in diameter are called pisoliths
(a) Concentric: Peripheral layers around small undetermined nucleus
(b) Radiate: Fibers radiating from small undetermined or large identifiable nucleus; may have several peripheral layers
(c) Sand-centered: Nucleus a quartz sand grain
(d) Massive: Interior of granular, smooth or chalk-textured material comprising nearly entire mass of spheroid
(e) Clustered: Attached ooliths without solid matrix
(f) Free: Unattached ooliths
(g) Drusy: Oolith covered with subhedral quartz; may be free, clustered, or aggregated by matrix
(7) Oomoldic: Residue containing oomolds which are spheroidal openings representing former presence of ooliths
(a) Skeletal with oomolds: Constituent material less than 25% of volume of fragment. Openings vary from microscopic to megascopic
(b) Abundant oomolds: Constituent material 25% to 75% of volume of fragment Openings vary from microscopic to megascopic
(c) Scattered oomolds: Constituent material comprising more than 75% of volume of fragment. Openings vary from microscopic to megascopic
b. Coarse:
(1) Unmodified
(2) Lacy
(3) Drusy
(4) Dolomoldic
(a) Skeletal
(b) Abundant
(c) Scattered
(5) Dolomorphic
(6) Oolitic
(a) Concentric
(b) Radiate
(c) Sand-centered
(d) Massive
(e) Clustered
(f) Free
(g) Drusy
(7) Oomoldic
(a) Skeletal
(b) Abundant
(c) Scattered
C. ANHEDRAL: No crystal form developed. (This includes quartz formerly referred to as vitreous and drusy.)
1. Loose:

FOOTNOTE 18. Ronald K. DeFord and W. A. Waldschmidt, "Oolite and Oolith," Bull. Amer. Assoc. Petrol. Geol., Vol. 30 (1946), pp. 1587-88.

End_Page 1483------------------------------
2. Aggregated: Well aggregated grains of any size, does not include detrital sand
3. Granulated:
a. Fine:
(1) Unmodified
(2) Lacy
(3) Drusy
(4) Dolomoldic
(a) Skeletal
(b) Abundant
(c) Scattered
(5) Dolomorphic
(6) Oolitic
(a) Concentric
(b) Radiate
(c) Sand-centered
(d) Massive
(e) Clustered
(f) Free
(d) Drusy
(7) Oomoldic
(a) Skeletal
(b) Abundant
(c) Scattered
b. Coarse:
(1) Unmodified
(2) Lacy
(3) Drusy
(4) Dolomoldic
(a) Skeletal
(b) Abundant
(c) Scattered
(5) Dolomorphic
(6) Oolitic
(a) Concentric
(b) Radiate
(c) Sand-centered
(d) Massive
(e) Clustered
(f) Free
(g) Drusy
(7) Oomoldic
(a) Skeletal
(b) Abundant
(c) Scattered
II. CHERT: Cryptocrystalline varieties of quartz regardless of color; composed mainly of petrographically microscopic fibers of chalcedony and / or quartz particles whose outlines range from easily resolvable to non-resolvable with binocular microscope at magnifications ordinarily used by petroleum geologists. Particles rarely exceed 0.5 mm. in diameter
A. SMOOTH: Conchoidal to even fracture; surface devoid of roughness; may be botryoidal; homogeneous; no distinctive structure, crystallinity or granularity
1. Chalcedonic: Transparent to translucent; smoky; milky; waxy to greasy; may be any color, generally buff or blue-gray; may be finely mottled. (This includes chert formerly referred to as transparent or translucent chert.)
a. Unmodified
b. Lacy
c. Drusy
d. Dolomoldic
(1) Skeletal
(2) Abundant
(3) Scattered
e. Dolomorphic
f. Oolitic
(1) Concentric
(2) Radiate
End_Page 1484------------------------------
(3) Sand-centered
(4) Massive
(5) Clustered
(6) Free
(7) Drusy
(8) Pseudoolitic: Rounded pellets with no peripheral layers or sharp distinction between pellets and matrix. Pseudoolith may be an oolith with peripheral layer absorbed or replaced
g. Oomoldic
(1) Skeletal
(2) Abundant
(3) Scattered
h. Granulated
i. Sandy: Containing sand grains
j. Silty: Containing silt grains
k. Banded: Varied color bands
l. Spicular: Containing sponge spicules. (Free spicules have been noted.)
m. Fossiliferous: Containing fossils or fossil fragments or cavities
2. Ordinary: Even fracture surface; all colors, chiefly white, gray, or brown; may be mottled; approaches opaque; generally homogeneous, but may have slight evidence of granularity or crystallinity
a. Unmodified
b. Lacy
c. Drusy
d. Dolomoldic
(1) Skeletal
(2) Abundant
(3) Scattered
e. Dolomorphic
f. Oolitic
(1) Concentric
(2) Radiate
(3) Sand-centered
(4) Massive
(5) Clustered
(6) Free
(7) Drusy
(8) Pseudoolitic
g. Oomoldic
(1) Skeletal
(2) Abundant
(3) Scattered
h. Granulated
i. Sandy
j. Silty
k. Banded
l. Spicular
m. Fossiliferous
3. Porcelaneous: Smooth fracture surface; hard, opaque to subtranslucent; typically china-white resembling china-ware or glazed porcelain; grades to chalky
a. Unmodified
b. Lacy
c. Drusy
d. Dolomoldic
(1) Skeletal
(2) Abundant
(3) Scattered
e. Dolomorphic
f. Oolitic
(1) Concentric
(2) Radiate
(3) Sand-centered
(4) Massive
(5) Clustered
End_Page 1485------------------------------
(6) Free
(7) Drusy
(8) Pseudoolitic
g. Oomoldic
(1) Skeletal
(2) Abundant
(3) Scattered
h. Granulated
i. Sandy
j. Silty
k. Banded
l. Spicular
m. Fossiliferous
B. GRANULAR: Compact; homogeneous; composed of distinguishable relatively uniform-sized grains, granules, or druses; uneven or rough fracture surface; dull to glimmering luster; hard to soft; may appear saccharoidal. (This is type of residue formerly referred to as crystalline chert.)
1. Fine: Individual grains difficult to differentiate
a. Unmodified
b. Lacy
c. Drusy
d. Dolomoldic
(1) Skeletal
(2) Abundant
(3) Scattered
e. Dolomorphic
f. Oolitic
(1) Concentric
(2) Radiate
(3) Sand-centered
(4) Massive
(5) Clustered
(6) Free
(7) Drusy
(8) Pseudoolitic
g. Oomoldic
(1) Skeletal
(2) Abundant
(3) Scattered
h. Granulated
i. Sandy
j. Silty
k. Banded
l. Spicular
m. Fossiliferous
2. Coarse: Individual grains easily recognizable (Grains rarely reach 0.5 mm. in diameter.)
a. Unmodified
b. Lacy
c. Drusy
d. Dolomoldic
(1) Skeletal
(2) Abundant
(3) Scattered
e. Dolomorphic
f. Oolitic
(1) Concentric
(2) Radiate
(3) Sand-centered
(4) Massive
(5) Clustered
(6) Free
(7) Drusy
(8) Pseudoolitic
End_Page 1486------------------------------
g. Oomoldic
(1) Skeletal
(2) Abundant
(c) Scattered
h. Granulated
i. Sandy
j. Silty
k. Banded
l. Spicular
m. Fossiliferous
C. CHALKY: Uneven or rough fracture surface; commonly dull or earthy in many cases; soft to hard; may be finely porous; essentially uniform composition; resembles chalk or tripolite. (Formerly referred to as dead or cotton chert. This includes dull unglazed porcelaneous material which grades into glazed porcelaneous material described under porcelaneous smooth chert. See II--A--3.)
1. Unmodified
2. Lacy
3. Drusy
4. Dolomoldic
a. Skeletal
b. Abundant
c. Scattered
5. Dolomorphic
6. Oolitic
a. Concentric
b. Radiate
c. Sand-centered
d. Massive
e. Clustered
f. Free
g. Drusy
h. Pseudoolitic
7. Oomoldic
a. Skeletal
b. Abundant
c. Scattered
8. Sandy
9. Silty
10. Banded
11. Spicular
12. Fossiliferous
III. ARGILLACEOUS MATERIAL
A. CLAY: Fine material of clay size
1. Sponge-like: Porous, earthy, fragile
a. Unmodified
b. Lacy
c. Dolomoldic
(1) Skeletal
(2) Abundant
(3) Scattered
d. Dolomorphic
e. Oolitic
(1) Concentric
(2) Radiate
(3) Sand-centered
(4) Massive
f. Oomoldic
(1) Skeletal
(2) Abundant
(3) Scattered
g. Sandy
h. Silty
i. Fossiliferous
End_Page 1487------------------------------
2. Flaky:
a. Unmodified
b. Lacy
c. Dolomoldic
(1) Skeletal
(2) Abundant
(3) Scattered
d. Dolomorphic
e. Oolitic
(1) Concentric
(2) Radiate
(3) Sand-centered
(4) Massive
f. Oomoldic
(1) Skeletal
(2) Abundant
(3) Scattered
g. Sandy
h. Silty
i. Fossiliferous
3. Massive:
a. Sandy
b. Silty
c. Fossiliferous
B. SHALE: All colors, many kinds of texture, hard to soft, may be porous, waxy, or granular
1. Smooth:
a. Flaky
b. Waxy
c. Laminated
2. Dolomoldic
a. Skeletal
b. Abundant
c. Scattered
3. Oolitic
a. Concentric
b. Radiate
c. Sand-centered
d. Massive
4. Oomoldic
a. Skeletal
b. Abundant
c. Scattered
5. Sandy
6. Silty
7. Fossiliferous
8. Glauconitic
9. Pyritic
10. Micaceous
11. Other minerals
IV. ARENACEOUS MATERIAL
A. SILT: Grains of silt size, chiefly quartz, but may be composed entirely or partially of other minerals
1. Loose grains
a. Quartzose
b. Glauconitic
c. Pyritic
d. Micaceous
e. Other minerals
2. Aggregates: All colors, many kinds of textures, hard to soft, may be porous
a. Poorly consolidated
(1) Quartzose
(2) Sandy
(3) Glauconitic
End_Page 1488------------------------------
(4) Pyritic
(5) Micaceous
(6) Other minerals
b. Well consolidated (chiefly siltstone)
(1) Unmodified
(2) Dolomoldic
(a) Abundant
(b) Scattered
(3) Oolitic
(a) Concentric
(b) Radiate
(c) Sand-centered
(d) Massive
(4) Oomoldic
(a) Abundant
(b) Scattered
(5) Sandy
(6) Fossiliferous
(7) Glauconitic
(8) Pyritic
(9) Micaceous
(10) Other minerals
B. SAND: Grains of sand size, chiefly quartz, but may be composed entirely or partially of other minerals
1. Loose gains
a. Rounded: Essentially spheroidal or ellipsoidal, coarse to fine
(1) Frosted
(2) Polished
(3) Etched
b. Subrounded: Polygonal shape but with well rounded edges and corners
(1) Frosted
(2) Polished
(3) Etched
c. Angular: Irregular plane or curved surfaces with sharp edges and corners
d. Regenerated: Secondary regrowth of crystal faces oriented with original axis of grain. Perfection of recrystallization controlled by adjacent particles
2. Aggregates: Generally white, brown, buff, red or green, depending on cement or constituents, hard to soft, may be porous
a. Poorly consolidated
(1) Rounded
(a) Frosted
(b) Polished
(c) Etched
(2) Subrounded
(a) Frosted
(b) Polished
(c) Etched
(3) Angular
(4) Regenerated
b. Well consolidated: (Chiefly sandstone) Grains described as below
(1) Rounded
(a) Frosted
(b) Polished
(c) Etched
(2) Subrounded
(a) Frosted
(b) Polished
(c) Etched
(3) Angular
(4) Regenerated
V. ANHYDRITE
A. MASSIVE
1. Fine granular: (Alabaster-like)
End_Page 1489------------------------------
2. Coarse aggregates:
a. Subhedral
b. Anhedral
B. FIBROUS
C. SUBHEDRAL
D. ANHEDRAL
VI. GYPSUM
A. MASSIVE: Includes alabaster
B. FIBROUS: (Satin spar)
C. SELENITIC: Cleavage plates or crystals
VII. ACCESSORY
A. SULPHUR
B. PYRITE
C. MARCASITE
D. SPHALERITE
E. MAGNETITE
F. HEMATITE
G. LIMONITE
H. FELDSPAR
I. MICA
1. Muscovite
2. Biotite
J. CHLORITE
K. GLAUCONITE
L. BARITE
M. CELESTITE
N. OTHER INSOLUBLE MINERALS
O. FOSSILS
P. PELLETS
Q. BEEKITE: Botryoidal, subspherical, or discoid accretions of opaque silica replacing organic matter, generally white
End_of_Article - Last_Page 1490------------

Acknowledgments:

(2) Standard Oil Company of Texas. Chairman of the insoluble residue conference.

Copyright 1997 American Association of Petroleum Geologists

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