Dear Dr. Nezafati,

from the structural point of view you can call it stockwork. I know this type which is characterized in neutral terms as a fitting breccia, typical of hydrofracturing. I became aware of this in many shallow, so-called epithermal, deposits in the southern part of South America, hosting Pb, Cu, Zn, Au, and In with a pervasive argillitization mainly of kaolinite-group minerals (kaolinite, dickite, halloysite) and pyrophyllite.

A major problem lies within the close link between the term "stockwork" and a particular type of deposit. It is often made by some geologists. The definition in itself does not show such a genetic link. Therefore, I used in addition to the wording "stockwork" also the terminology  "fitting breccia" . The genetic interpretation should not be done too hastily in terms of any attribution to one or the other type of deposits and a proper and precise description is often more valuable than pigeonholing a deposit based upon one characteristic feature.

Mit herzlichem Glückauf !

Harald G. Dill

For me, first picture upper left display a set of filled fractures parallel to each other. The compression mode of anisotropic stress (S1>S2>S3) is responsible to create this type of fracture set. Later on hydrothermal fluids filled this fracture set.

Upper right picture give a glimpse of bending bed/layer (fold) comprising open-mode fractures parallel to the hinge of the fold.

Lower picture with middle piece of rock sample consists of three sets of fractures were created in T1, T2 and T3 time intervals. Along a fracture set, offset is also visible.

Perhaps hydrothermal fluids filled these different set of fractures contamporaneously.

Regards

IJAZ 

Dear Colleague Nima

Your pictures show us the typical samples of a Stockwork mineralization, which are accrued mostly in Cu-Au and Cu-Mo mineralization with more or less 0.4-1 %/t Cu. there are different types of such occurrences with respect to the alteration processes as well as mineralization process. In USA-Canada-south Sweden and Zair. These kinds of Stockwork or figures on the stones are cussed with respect to the fractional crystallization via cooling in a magmatic system with incompatibles elements. In such systems and specially in your samples the amount of Magnetite and Augite is very important because they are the most important Cu bearing phases. the filling in the pictures is not always randomly and the figures are in fact typical for such terms. in any cases please see Anderson (1980).

Yours very faithfully

bleibe dir mit den herzlichen Gruesse aus Isfahan

Amin 

Dear Professor Dr. Dill,

Many thanks for your comment and your as always thoughtful and useful remarks.

I fully agree with you that only one feature should not be used for genetic interpretation of ore deposits.

Mit herzlichen Dank und Glückauf,

Nima Nezafati

Dear Mr. Ijaz Ahmad,

Many thanks for your interest and your answer.

Your are right, although I did not see any folding in the area.

Best regards,

Nima Nezafati

Dear Amin,

Many thanks for your remarks.

Herzliche Grüße,

Nima

Dear Dr. Pintea,

Many thanks for your useful comment.

Yes, many of veinlets are composed of (oxidized) sulfide minerals plus quartz.

I agree that fluid inclusion studies can be of help.

Kind regards,

Nima Nezafati

yes

Dear Mr. Nezafati,

I would also call this a stockwork

KInd Regards,

Jack Voncken

Dear Mr. Nezafati,

Yes, I think it is stockwork, generally it occurs in metal deposits. Its formation is that some kind of vein fill in the  fracture of  the rock.

Best wishes.

Xiang Gao

Yes, this is a stockwork.  Random orientations is not a requirement for a stockwork and there are even parallel, sheeted vein stockworks.

Dear Dr. Voncken,

Thank you for your kind comment.

Kind regards,

Nima Nezafati

Dear Dr. Xiang Gao/Dear Mr. Ken Krahulec/Dear Dr. Abdulkader Afifi,

Many thanks for your comment.

Best regards,

Nima Nezafati

What you have is a typical porphyry style mineralization which presents as stockworks of disseminated Cu-Mo-Au minerals. The hydrothermal breccia is another strong evidence for such porphyry system. The lack of massive sulfide mineralization is another evidence of porphyry system.

best regards.

Ahmed

The term "stockwork" is not really genetic (in fact I tend to think of it as more a descriptive mining term and I tend to use structural terms in preference). For example, a series of parallel veins is commonly a tension-vein array (but they can be large, extensive strike-length and more isolated but also tensional, related to things like roof collapse with magma withdrawal). I rarely see vein systems that could be described as truly random. Even with fracture sets directly related to intrusive emplacement centres, or the collapse of roof zones, the veins are commonly sets of concentric, radial and parallel (including - but not only - en echelon) fractures, often superimposed on each other. Good descriptions would be an early paper in Economic Geology on the Henderson-Urad Mo multiple intrusions and successive radial and concentric fracture sets, or early papers in the same journal on Au vein systems related to collapse in the San Juan volcanic field of Colorado.

I think, its sheeted vein and less stockwork, 

From picture i see that rocks has weathered or have supergen process become oxide... oxidation and supergen process create clay mineral (kaolinite, illite, alunite in acid condition).. veinlet or sheeted fracture was replaced by Fe oxide (hematite-jarosite), 

Dear Nima: I also don't believe it is a stockwork, not in the mining sense of the word, at least. Normally stockworks are associated with the cupolas os Cu-Mo porphyries, and they encompass large volumes (seveal km3) of fractured rock at a centimeter to decimeter scale level. So I think you don't have either a stockwork or a skarn. Just a set of parallel tension veins. veiRegards. Sebastian.

Dear Mr Nezafati

The term stockwork describes a network of veinlets, usually (but not always) associated with alteration processes linked with mineralization. So yes your photos most probably belong to stockwork.

Kind Regards

George Christidis

Yes, those who work with porphyry copper deposits tend to think the term is used only for those deposits, but it is used for many others types as well (even orogenic gold). So Sebastian and GE Christidis are both largely or completely correct. However that is one reason that I prefer more specific terms if possible.

N.B. When I mentioned the San Juan Mts example earlier I was thinking of early papers on the Creede caldera there (widely-spaced large parallel veins in the magma chamber roof). Henderson-Urad is a classic for radial and concentric patterns.

Dear Nima, another point that should raised is: Do you have any evidence that this sheeted veins array continues in depth? In order to be stockworks should do so.

Stellios

That is not really part of any definition of stockwork

Dear Ahmed,

Many thanks for your comment.

Best regards,

Nima

Dear Dr. Martin James Hughes,

Many thanks for your comments and the useful information.

I agree with you that this type of mineralization is not restricted only to Cu-Mo prophyry deposits. Anyhow, the other geological features in the prospect of interest (e.g. presence of extensive clay-alunite alteration in a plutonic-volcanic area, mineralized breccia, etc. ) favor more or less a porphyry or epithermal type of mineralization.

The point was, this type of parallel sets of veinlets (although in some cases cross-cutting) were rather new to me and as mentioned before, I was not sure if I could call them stockwork.

Best regards,

Nima

Dear Mr. Okki Verdiansyah,

Thank you for your comment.

Correct! The veinlets seem to be sheeted veinlets, but in many cases two or three sets of sheeted veinlets crosscut eachother.

And some supergene processes have occurred in the area too. That is why the original sulfide-silica veinlets have converted to oxides.

Best regards,

Nima Nezafati

Dear Sebastián,

Many thanks for your comment.

I am not sure if there is a copula there, (especially because there are no subsurface data available yet) but the major rock units in the area are volcanoplutonic which are highly altered. 

And the fractured-mineralized rock (if not stockwork) has a rather considerable extension (at least 1km2).

We did not find any evidence for a skarn mineralization in the area.

Best regards,

Nima

Dear Dr. G.E. Christidis,

Thank you for your comment.

Kind regards,

Nima Nezafati

Dear Stellios,

Thank you for your comment.

There are no subsurface data available yet, but since the outcrops of such veinlets are visible on top of the hills and the bottom of gullies, I guess that the vertical extension of such a mineralization should be at least around 100m.

Best regards,

Nima

Thank you Nima

Thanks a lot. I am also working on a skarn deposit at Greece, which is very complex, as it has both Ca- and Mg-skarns

Best regards

It looks like stockwork, however, the typical stockwork minerlisation are found in greisen or altered granite. The hydrothermal fluids seem to follow the bedding planes or other structurally weaker zones as shown in the photographs.

Regards

Mohammad Zahid 

Nima says the rocks are volcanic so no bedding - and stockworks can be in any rock type and in deposits of many types of metals. We all tend to draw on our own areas :-).

According to the AGI Glossary of Geology (Jackson and Bates, 1968) a "stockwork is a mineral deposit consisting of a three-dimensional network of planar to irregular veinlets, closely enough spaced that the whole mass can be mined." There is no requirement that the veinlets be randomly oriented.

Stockworks of veinlets that comprise ore zones in Porphyry-Cu and porphyry-Mo deposits tend to be very large and more-or-less cylindrical to dome-shaped. Although veinlet orientations may appear random in small samples, overall patterns may include conjugate sets of veinlets, related to the stress field that was dominant during fracturing and mineralization. Where maximum principal stress was vertical and lesser horizontal stresses were subequal, radial and concentric vein sets may predominate. 

"Stockwork" can also be considered roughly synonymous with "network deposit," or "stringer lode." Therefore, if a network of veinlets is relatively small, or is more-or-less tabular, a better description might be "tabular network," or "tabular stringer lode."

Dear Dr.  Hughes/ Dear Dr. Mohammad Zahid Khan,

Thank you for your comments.

Kind regards

Dear Dr. Bookstrom,

Many thanks for your useful comment.

With kind regards

It is looking like stockworks.

the following link shows a few pictorial representaion.

http://www.nr.gov.nl.ca/nr/mines/prospector/matty_mitchell/Virtual/Guide-to-Epithermal-Gold-Deposits.pdf

https://mineral.cuso.ch/fileadmin/mineral/document/1-Epithermal-Deposits.pdf

A few links on their detailed study.

https://www.911metallurgist.com/blog/wp-content/uploads/2015/10/Models-and-Exploration-Methods-for-Major-Gold-Deposit-Type.pdf

http://www.geo.arizona.edu/~mdbarton/MDB_papers_pdf/Inverno[08_FeitaisVMS_EG.pdf

All the best

Thank you Ms. Girishbai for the useful links and the information.

All the best

In geology, a stockwork is a complex system of structurally controlled or randomly oriented veins. Stockworks are common in many ore deposit types and in greisens. They are also referred to as stringer zones.

Dear Nima: the sample in the bottom (larger) picture you annexed shows three main sets of veinlets, but it is too small to define the studied zone as a stockwork, since these tend to be quite large volumes of fractured rock with closely spaced ore veinlets. Your veinlets are indeed closely spaced, and show some conjugated veins also. The Cu-Mo, Cu-Au, and Mo porphyry, and most epithermal lode deposits, usually have reserves in the order of hundreds of Mt or even Gt, if you can delineate a large sufficient volume of these fractured and veined rocks, then you will have a stockwork. Regards, Sebastian

It is certainly a kind of stockwork that resembles porphyry type environment and therefore of interest in mineral exploration. Whether it is distal to an economic deposit in the area depends on additional exploration.

Once again, a word or an appelation is important when there is a genetic relation to it. Also with the time, the origin of word get tinted by people using it without geoscientific rigor. Thanks for asking opinion from your pairs.

Stockwork is commonly associated to PCS (Porphyry Copper System), and the more then 3 directions of veinlets is important, because any cinetic fracturation will provide 3 complementary ''dislocation''. I think that randow orientation component is important because it is a expression of desequillibrium in the distribution of adjustement of stress and relaxation impose to rocks.

We have to remember that PCS are mostly interpreted as post-orogenic and are form in collapsing environment. Relaxation will create these random fractures and dislocation which are ''short cut'' for the relaxation of the adjustment of the fragmented blocks over the magmatic chamber.

To keep it simple, lets avoid the lithologies composition and their fracturation's pattern, which has also a huge impact in the distribution of fracturation.

Finally, to give my opinion on your rocks, I would use term ''oriented veinlets stock'', because veinlets seems straight and show an organised distribution. But I agree with Sebastián Grande that the samples are too small to have a proper idea of the veinlets distribution.