Processing of granite for the columns of St. Isaac's Cathedral, document analysis, part 2

2024 Author: Seth Attwood | [email protected]. Last modified: 2023-12-16 15:55

After writing the article Processing of granite for the columns of St. Isaac's Cathedral, there were many comments and, in particular, a question was asked about the obelisk at the Moscow railway station in St. Petersburg.

This is a very fair question, which required an answer from a specialized specialist. The essence of the question was as follows. In the article I brought up a dialogue with Doctor of Geological and Mineralogical Sciences Marina Yuri Borisovich, who said that the use of fractured outcrops of granite rocks for the production of large high-quality products is impossible. That is, it is impossible to use deposits in which there are horizontal and vertical cracks for the production of columns of St. Isaac's Cathedral. And in relation to the Puterlax field near Vyborg, from which the columns were allegedly made (and in general the floor of St. Petersburg), it is written in the documentary and fiction of the 19th century that the rock outcrops have a fractured structure and along these cracks the breaking of blocks took place. In general, there are two mutually exclusive theses. And the example with the stele at the Moscow railway station went against the words of Y. B. Marin. As you know, the stele is made of a monolith broken out in the Renaissance quarry, and the description for it says that it broke out just along natural cracks. The stele is 22 meters long (the blank was 22.5 meters). This is the second largest monolith after the Alexander Column (processed 25.6 m). In the comments, I promised to deal with this issue and in fact this article is just about this.

To clarify the situation, I applied to the St. Petersburg Mining University in writing. Ivanov Mikhail Aleksandrovich, Professor of the Department of Mineralogy, Crystallography and Petrography, Doctor of Geological and Mineralogical Sciences, kindly agreed to answer my questions. For which many thanks to him. Actually, as an answer, Mikhail Alexandrovich sent me his last work, it was dedicated to the Renaissance career. The work is voluminous, multi-page and there is absolutely no point in putting it here. It is written for specialists and is written in a language that is difficult to understand, replete with specialized concepts and terms. I will only present in a thesis what is of interest on the question posed.

So the point. To begin with, a scan of the first page from the work of M. A. Ivanov.

Already on the first page we see that, indeed, in the Vozrozhdeniye quarry there were huge monolith outcrops, up to 10x15x60 meters. And this is a fact noted by modern research and documents. Actually, the stele at the Moscow railway station is direct evidence of this. However, in this case we are talking about gray granite. The columns of St. Isaac's Cathedral are made of another kind of granite - pink rapakivi. So what's with the pink rapakivi? There is also an answer for it.

We read in black and white that pink rapakivi is characterized by increased fracturing and, as a block stone, is of less interest. This is exactly what Yuri Borisovich Marin once told me, in relation to the columns of St. Isaac's Cathedral in particular and pink rapakivi in general. A natural question arises, what is this fracturing? After all, the concept of "increased fracturing" is rather arbitrary. And then we find the answer.

I highlighted in red. Pink rapakivi does have very large fractures. The layers have a step of 20-50 cm. So that's it. At the same time, gray granite can have sub-horizontal gaps (cracks) from 2-3 to 8-9 meters, and in exceptional cases up to 10-15 meters, as in the case of the monolith for the stele at the Moscow railway station. It is also very important that this fracture of the pink rapakivi is revealed only when it is split. A very important clarification.

The article is certainly good and, in general, gives an answer to the question posed. However, I am a rather meticulous person by nature, I cling to trifles, and in my personal correspondence with Mikhail Alexandrovich I clarified a number of points directly. I will outline the essence and answers in a thesis.

Question - in the article we are talking about the Renaissance career. How applicable is the analogy with the quarry in Puterlax, in which the monoliths were allegedly cut down for the columns of St. Isaac's Cathedral and the Alexander Column?

Answer: this (Renaissance quarry) is not a classic rapakivi (vyborgite), but nevertheless their closest relatives, both in their geological nature and in terms of development.

Question- has there been any modern research in Puterlax, is there documentary evidence of what is described in 19th century fiction and documentary?

Answer: I do not know that in Puterlax the Mining Institute ever studied the state of fracturing of the rapakivi massif, and also determined the technology used in ancient times to separate large stone blocks from the massif.

Question- the article says that the fracturing of gray rapakivi is up to 8-9 meters, while it is indicated that there are also monoliths measuring 10x15x60 meters. How typical are these huge monoliths?

Answer: In the northern part of the Vozrozhdenie granite quarry in the early 80s, a section of the massif was uncovered, in which it was possible to observe a horizontally lying granite deposit, with a thickness of about 10 m and a strike length of more than 60 m. It was from it that the monolith was split off for production columns for the Vosstaniya square. The rest of this deposit is shown on the geological map and sections in my article.

In addition, I received a number of answers to the questions posed, which I had previously asked Professor Yu. B. Marina.

Question- How can you comment on the information that granite is relatively soft for the first 4-5 days and then hardens. As an example, I sent a scan of Mevius to the Mining Journal in 1841

Answer: I am not aware of any cases of "hardening" of rapakivi granite (and, in general, hardening of igneous rocks) after the separation of their blocks from the massif. It is theoretically impossible to admit the possibility of such a change in properties. At the same time, I can assume that "superstition" arose in connection with the known ability to harden another building stone - calcareous tuff, the so-called "Pudost" stone from the tributaries of the Okhta River near Gatchino. This is the same stone that Voronikhin used for the construction of the Kazan Cathedral. Indeed, after being extracted from the bowels, it is at first easily cut with a steel tool, but after a while, due to the recrystallization developing in it, it noticeably hardens. This was known to the builders of that time, and it is possible that it was profitable for someone to think about rapakivi in the same way.

Question- in this case, how can you comment on the information of your colleague Professor A. G. Bulakha in the book Stone decoration of St. Petersburg which explains the hardening of granite by the theory of relaxation. There are also wave and fluid theories trying to explain the hardening of granite.

Answer: Disputes about the "hardening" of granite are pointless, since there is no theoretical basis for this, no experimental data, no experimental evidence.

Question- Mevius writes that when separating granite blocks, holes were drilled with a diameter of 2.5 cm and a depth of 8.5 meters. I sent the scan. The techies say it's impossible. At such a depth of boreholes, the impact force of the hammer will be damped by the springing properties of the rod and sand (crumb). Is there any documentary evidence of such processes?

Answer: Drilling bore-holes manually by the percussion-rotary method with a depth of 8, 5 m and a diameter of 2, 5 cm, in my opinion, is theoretically possible, but in practice it is very difficult. At the same time, the objections of the "specialists" are countered by the fact that chiselling of such deep holes can be carried out not with the blows of the sledgehammer on the bar, but with the blows of the bar itself, falling to the bottom under its own weight. The destruction of rocks by wedging boreholes driven by steel bits has been known since ancient times. I personally met people in the Siberian regions who worked in such a way in the deposits of mica, breaking out its crystals from granite pegmatites in the pre-war years. I saw and held in my hands their tools: steel chisels with a hardened tip, devices for rotating the chisel in the hole and removing cuttings from it, as well as ordinary hand sledgehammers. In cases known to me, the depth of holes drilled in this way ranged from 0.5 to 2.0 m.

In the last question, I did not begin to breed controversy, given that Mevius says about the use of sledgehammers and the passage of not only vertical boreholes (holes), but even close, as in the case of the Alexander Column. And how, in this case, the possibility of drifting towards the borehole was excluded? In this case, the answer of a specialist was important to me that only boreholes with a depth of 2 meters are documented.

That's basically all. There were more questions and answers, but they are outside the scope of this article. What are the conclusions in general. Yes, all the same. There is no scientific and reliably documentary evidence of a career in Puterlax. From the word at all. Only works of the 19th century. There are no theories of granite hardening. The example with the gray granite stele at the Moscow railway station is not applicable to the pink rapakivi granite rocks.

As for the sayings of a certain Mevius, for whom, by the way, we do not know either name or patronymic, but to which all chronologists and historians refer to since the middle of the 19th century, it is possible, or rather necessary, to be recognized as insignificant. That is, they do not have any historical value because they contradict common sense and are not confirmed by practice. It is possible that this is a banal late falsification. Clumsy, absurd, but nonetheless. Let me remind you that it is Mevius who is the primary source and indisputable authority for all adherents of the official version of the construction of St. Isaac's Cathedral and the Alexander Column. The second such basic authority is Montferrand himself, whose extremely unprofessional work I have analyzed in detail in articles on Isaac and the Alexander Column.

On this I take my leave, everyone who read it, thank you very much.