The term texture is used for metamorphic rocks as well. There are text books and atlases on metamorphic textures (eg. Alan Spry 1969. Metamorphic textures, Pergoman press, Oxford. B.W.D Yardley, W.S. MacKenzie, C. Guilford. 1990. Atlas of Metamorphic Rocks and their textures. Addison Wesley Longman (Pearson Education ISBN: 0582301661). Please see my answer to a similar question on Research Gate: What is rock fabric?

https://www.researchgate.net/post/What_is_rock_fabric

Fabric is a term used for both structure and texture in all three kinds of rocks in the earth's crust. There are also books on sedimentary structures (eg.Zhong, Jianhua, Grapes, Rodney, 2014 (to be published october, 2013, Atlas of Sedimentary Structures, Springer, ISBN 978-3-642-23107-0) and igneous structures. Texture is commonly used for observations made on small samples and under the microscope, to indicate grain sizes, grain shapes, and mutual relationship between mineral grains.

According to most petrologists, fabric means observable characteristics of rocks, which can be studied in outcrop, hand specimen and under microscope. Fabric incorporates both texture (sometimes called microstructure) and structure. On the other hand, texture refers to small-scale features in a rock including grain size and shape, intergranular relations, and degree of crystallinity (amount of crystal and glass) generally observed at the scale of a hand specimen and using microscope. Many geologists also use fabric as a synonym for texture.

Another thing to note that the term “fabric” more frequently applies to the directional features in both sedimentary (pebble imbrication) and metamorphic rocks (gneissosity, etc.) than to those of the igneous rocks.

One of the main confusions regarding usage of the terms fabric, structure and texture arise from nature itself. For example, foliation is a planar, directional feature, produced by penetrative deformation in metamorphic rocks, which is observable at all scales, ie. at outcrop or quarry scale, hand-specimen scale or under the microscope. Therefore, depending on at what scale a person made the observations he may use the words foliated-fabric, foliated structure or foliated-texture. If one (a beginner) is unaware that foliation is a penetrative fabric, he will be confused by such usage. Because foliation is a penetrative fabric it occurs both as a structure and texture. A layered fabric may do the same depending on the scale of layering. If the layers are very thick one may observe that in outcrop but not under the microscope (unless one makes a slice containing marginal region of two layers).

Thank you L.R.K Perera and S M Mahbubul Ameen for the answer. Still my confusion is that can we used the term fabric instead of texture and structures of a rock like schistose fabric, gneissos fabric, clastic fabric, equigranular fabric etc. because the term fabric incorporates both texture and structure. If we can used this term fabric for all scale then its fine and if we can't used the term fabric in all scale then how will we classify them.

Dear Chaitradhar,

There is no harm in the usages like schistose fabric, gneissose fabric, clastic fabric, equi-granular fabric etc. and many people do use it that way. But it is more appropriate if one uses the terms like schistose texture, gneissic texture, equi-granular texture and clastic texture when describing those fabrics in small or hand-specimens and under the microscope. Sometimes clastic textures and equigranular textures are not obvious in outcrop but are better seen under the microscope. Then, it is better to avoid the term fabric. Schistose and gneissose features on the contrary may be better seen at all scales. But as a principle it is always better to reserve the word texture for observations made in hand-specimens and under the microscope, and use structure for observations made in large exposure, and the word fabric when you want to refer to both structure and texture together whenever both are penetrative fabrics. As mentioned in a previous answer, foliations and lineations are commonly products of penetrative deformation (i.e. deformations that affected the rocks at all scales). But remember, that there are very local developments of foliations/lineations whenever the deformations had not been intense or when the strains were confined to local areas like shear zones or axial planes of folds. Then, in the usage you have to be very specific, ex. axial plane fabric, shear fabric when referring to those foliations and lineations. Hope this will be of help to you. Cheers!

Thanks L. R. K. Perera for clearing my doubts..actually it was very difficult for us (as a begginer) where we use the appropriate terminology though there is no limitation for usage. Sir, it will be better if there is an Internationally accepted scale for these three term which will help in future and reduce the confusions. Thanks again..

Dear Chaitradhar,

There is IUGS (International Union of Geoscientists) sub-commission on Metamorphic rocks which started making recommendations on terminology for use on metamorphic rocks. But you will see in the attached document that the use of the terms texture and micro-structure had been a difficult issue for them too. IUGS recommendations on metamorphic rock naming is also attached herewith. You can download various other recommendations of the sub-commission from the link given below.

http://www.bgs.ac.uk/scmr/products.html

Chaitradhar, Sorry I forgot to attach the naming part which is now attached.

In my opinion, texture refers more to relative grain boundary relationships (including paragenesis, replacement aspects, size/shape variations for the different grains/minerals, etc., and hence the emphasis is more on grain boundaries and intergrain relationships) whereas fabric refers to the geometric aspects of arrangements of grains or minerals, parallelism defining planes (foliation) or lines (lineation) in a rock. Note that the grain shapes are not necessarily relevant to defining lineation or foliation; that is, equant grains arranged in lines or planes can still define lineations and foliations, respectively, and therefore define the rock fabric. However, it is not unusual that grain shapes also are arranged parallel to the geometric distributions of the

grains in defining rock fabrics.

I agree with William Macdonald but will state more explicitly that texture refers to the crystallographic alignment of grains. This definition becomes more evident when one examines the metallurgical literature, in which many of the same processes are investigated with many of the same techniques as in the geological literature. For a modern reference in the Earth sciences, see the new book by Heilbronner and Barrett titled "Image Analysis in Earth Science."

I agree with William Macdonald that paragenesis and replacements aspects too are part of texture, if one wants to be specific and elaborating on the equilibrium and disequilibrium among minerals in a rock, particularly in a metamorphic rock. However, replacement textures are not always present and a paragenesis cannot be given for a monomineralic rock, thus, in describing the word texture it is better to say that it incorporates sizes, shapes and mutual relationships between grains. In my opinion, fabric involves more than “the geometric aspects of arrangements of grains or minerals”. In this regard I quote from pages73 and 74 of Hobbs et al’s (1976) book ‘Outline of Structural Geology’. They wrote: “The term fabric, when applied to rocks, includes the complete spatial and geometric configuration of all those components that make up the rock. It covers terms such as texture, structure, and preferred orientation and so is an all encompassing term that describes the shapes and characters of individual parts of a rock mass…….” They stress that “the individual parts referred to are only considered as contributing to a fabric if they occur over and over again…. ” or “Features that do contribute to a fabric are said to be penetrative….” Sometimes, a foliation and/or lineation could be only locally developed, and according to Hobbs et al, then it cannot be treated as fabric. They use the term microfabric for penetrative features observed under microscope or electron microscope and include microstructure and crystallographic preferred orientation under that. Further, they go on to say that, “microstructure is what is referred to as texture in many geological texts” and “the term texture is used to mean crystallographic preferred orientation in studies of metals and ceramics” in materials science. For the latter Hobbs et al prefer the term microstructure, apparently in disagreement with L. Hansen’s preferred usage of the term texture from a point of view of metallurgical science (perhaps according to the text he referred to). The above taken together with Macdonald’s and Hansen’s and many others points of view explains how complicated the usages of the terms fabric, structure and texture.

Thank you L. R. K. Perera, L. Hansen, S M Mahbubul Ameen and William Macdonald for your valuable answer. Though the complicacy is its appropriate usage but my confusion is clear. The main difficulties of usage of the term fabrics is only with metamorphic rocks ( foliation & liniation) not with others. Thats why I was asking

why fabrics terminology is used largely in metamorphic rocks. As L.R.K. Perera already replyed me that there is no harm of usage fabrics instead of texture and structure but it is better to use its appropriate terminology if it is possible. Anyway thank you again...........

I think texture is used to explain feature in mineral scale, but fabric is used to explain changes in rock body due to tectonic activities, i.e. when a rock goes under tectonic stress and it shows foliation and lineations in field scale.

Habib Alimohammadian, I agree with your answer and it clearly explains the basic difference of texture and fabric. The term fabric can be used in all scale and it incorporates both texture and structures. So, according to my questions can we say that the terminology fabric (i.e. fabric term is used to explain the changes in rock body due to tectonic activities) is mostly used in metamorphic rocks because only metamorphic rock shows foliation and lineation when it goes under tectonic stresses.

Actually there is no hard and fast rule to say that, this terminology is only used in metamorphic rocks but it seems that from all the answers fabric terminology is mostly associated with foliation and lineation, not with the other rock types.

Chaitradhar, I want your attention on the quotations from pages 73-74 of Hobbs et al's book I have given above. Fabric is not only applied to features in a rock body resulting from tectonic forces. There are layered fabrics in igneous rocks, metamorphic rocks and sedimentary rocks which have nothing to do with tectonics. There are clastic fabrics in sedimentary rocks (i.e. a fabric indicating that a rock consists of broken fragments of pre-existing rocks.) The most important fact is that a fabric has to be penetrative. That is, it should occur again and again throughout the rock mass.

Many authors (i.e., the school from Basel) consider the term "texture" related to crystallographic preferred orientation, as L. Hansen said. In this case, "fabric" could be related to all other aspects of the rock (SPO, grain shape, microstructures, etc).

Texture (grain-grain relationships) refer to:

1) shape and size of the individual grains

2) orientation of individual grains

3) arrangements of the mineral grains in the rock

Fabric refer to the complete spatial and geometric configuration of textural and structural elements.

Dear Chaitra Dhar Taye ,

I think I became an expert on this topic, because I had two reviewers of my PhD thesis that had opposite views of how structure, fabric, and texture should be used.

Indeed, this is one of the many examples of two terms which are used interchangeably by people in some fields and have different meanings in other fields. What you say is related to the fact that structural geologists prefer fabric/structure (and microfabric, microstructure) with respect to texture, which is favored by material scientists and petrologists.

According to Passchier & Throuw. Microtectonics (2006). 'fabric' is the complete spatial arrangement of all components in a rock' and covers concept such as 'texture' and 'structure'. They call 'fabric elements' the individual elements that make up a fabric and use fabric and structure as synonims. These authors suggest not to use 'texture' because material scientists have used it to refer to LPOs (lattice preferred orientations), as Sebastián Oriolo already said.

Not many structural geologists agree with the use of 'fabric' and 'structure' as interchangeable terms and some use fabric as something made by the arrangement of structures, with an oder of magnitude > structure. E.g. a rock with a foliated fabric is made by parallel structures/layers.

Other textbooks (e.g. Bucher & Frey, 1994 and older) make a distinction between texture = geometrical aspects of the components of a rock and structure (e.g. size, shape, etc.) = presence of compositional layering, folds, etc.

As you can see there are field-specific and author-specific distinctions. I have personally stopped using fabric, as different reviewers have a different take on its meaning and it's complicated to use it when submitting a paper. I always use structure and microstructure for everything. I also avoid using texture to avoid confusion with material science.

Finally, please note that the IUGS in Metamorphic Rocks: Classification and glossary of terms recommends substituting 'texture' with 'structure'

In my opinion, texture regards sizes, shapes and physical arrangement of particles or grains, fabric includes texture and structure, both microscopic and mesoscopic or macroscopic.

In my opinion, texture regards sizes, shapes and physical arrangement of particles or grains, fabric includes texture and structure, both microscopic and mesoscopic or macroscopic.

In the literature there exists a wealth of confusion with regard to the terminology of rock fabrics, for example:

(1) ..." The structure of a non crystal is the geometrical configuration of its elementary parts and of any characteristic features to which the arrangement of these parts gives rise"..., the geologic used term fabric is synonymous with "texture" in this usage..." (Paterson & Weiss, 1961)...

(2) ....." crystal or petrofabric properties of a rock (e.g. crystallographic or lattice preferred orientation) and dimensional or microstructure properties (e.g. dimensional preferred orientation)...." (Lloyd, 1994)....

(3) ......"metamorphic textures and microstructures. The term texture is used in the conventional geological manner for spatial relationship between mineral grains in a rock, and for such features as grain shape and size; combined with microstructures such as layering, xenoliths vesicles and orbs"...." There has been a tendency in some of the modern research literature to use the word "texture" in its metallurgical sense for preferred orientation. Much as we owe to metallurgy the concept of mineral preferred orientation development, I regret the borrowing of its usage when texture already has such a long-standing and diferent usage in geology.... (Shelley, 1992)

In the US texture was usually restricted to scalar quantities such as grain size and types of grain shape or of grain contacts, etc. "FABRIC" is the English translation (Knopf, 1933) of the German term "GEFÜGE"...." Die Raumdaten im inneren eines betrachteten Bereiches beschreiben dessen Gefüge, ihre Änderung beschreibt die Änderung des Gefüges; die (statistische) Symmetrie der Raumdaten in ihrer Gesamtheit beschreibt die Symmetrie des Gesamtgefüges. Die Wahl der Raumdaten erfolgt in Auslese für ein bestimmtes Interesse, auf welches die Beschreibung des Gefüges bezogen wird....." and was introduced by Sander (1930), for the very good ENGLISH translation see Sander, 1970) to overcome the difficulties with the usage of the terms mstrctrue and texture in the sence of Grubenmann (1904)

Turner & Weiss (1963) also offered a broad definition of fabric.According to them fabric includes all structural and textural features of a rock which are manifested from the crystal structure to the mountain range...

see discussion and summary in "Siegesmund 1996. Geotektoniche Forschungen 85 ......, "The significance of rock fabrics for the geological interpretation of geophysical anisotropies"......

The difference is that texture is the feel or shape of a surface or substance; the smoothness, roughness, softness, etc of something while fabric is (originally|construction) structure, building.

Dear Siegfried,

I think that the confusion, which you emphasize, is due to the different use of these terms in the different disciplines of earth sciences. For example, also the concept of structure is different in mineralogy or crystallography with respect to structural geology.

As noted by many people, the terms are used differently depending on discipline. In structural geology, fabric is the most general term which covers shape, grainsize, microstructure, and preferred (shape and lattice) orientations (Hobbs, et al. 1976) whereas the term texture is rarely used. In petrology, texture is specifically used for relationship among grains etc. In materials science, the term texture is often used to mean Lattice Preferred Orientations.