Geological Survey of Finland GTK Open File Work Report Energy and Construction Solutions

5.8.2021

Pre investigation of the wonderful stone constructions of St Petersburg with special emphasis of Rapakivi granites and restoration possibilities with original stones Mika Räisänen, Heikki Pirinen, Elena Panova, Vasily Litvinenko and Paavo Härmä

Russian Academy of Arts during the beautiful sunrise

Funded by the European Union, the Russian Federation and the Republic of Finland

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GEOLOGICAL SURVEY OF FINLAND DOKUMENTATION PAGE 5.8.2021

Authors Type of Report Mika Räisänen, Heikki Pirinen, Elena GTK Open File Work Report Panova, Vasily Litvinenko and Paavo Härmä Commissioned by CBC 2014‐2020 SOUTH‐EAST FINLAND‐. Funded by the European Union, the Russian Federation and the Republic of Finland.

Title of Report Pre investigation of the wonderful stone constructions of St Petersburg with special emphasis of rapakivi granites and restoration possibilities with original stones.

Abstract According to UNESCO, St. Petersburg has an outstanding historical universal value. The city has preserved its historic appearance and beauty and its sites have been maintained and respecting not only the cultural landscape but also the smallest details. The aim of the NaStA‐project is to expand and strengthen the operating environment for SMEs by increasing knowledge about the use of natural stones and related business opportunities in the fields of cultural and historical heritage. The main measures of the project include studies on the demand for original natural stone resources in buildings and construction (restoration needs), as well as the availability of suitable material for restorations. This goal is supported by researching and classifying the types of stone used in historic buildings, as well as developing methods to make restoration materials less noticeable and functional with different surface treatments. In this work, we focus on observing the restoration methods and materials used mainly in rapakivi granite buildings and sites to support Russian‐Finnish cooperation.

Keywords Natural stone, building stone, World Heritage Site, quarry, restoration, St Petersburg, rapakivi granite, Virolahti, pyterlite rapakivi granite

Total pages Language Confidentiality 21 pages English Public Archive code Unit Energy and Construction Solutions 41/2021 Signature Signature

Head of Unit Hannu Lahtinen Senior Specialist Mika Räisänen

Geologian tutkimuskeskus | Geologiska forskningscentralen | Geological Survey of Finland

Table of Contents Documentation Page

1 Background and aims 1 1.1 The historic center of St Petersburg 1 1.2 NaStA‐project 2 1.3 Origin of natural stone resources 2 1.4 Spectacular natural stone logistics and construction 2 1.5 The Alexander Monument as an excellent example of skillful restoration 4 1.6 Sites of pre investigation 4 2 Bridges, river banks and street construction 6 2.1 The quay in front of Russian Academy 6 2.2 Lomonosova bridge over river Fontanka. 8 2.3 Griboyedov channel next to Kazan Cathedral 10 2.4 First winter bridge and Venetian landscape 10 3 Buildings, churches and monuments 12 3.1 The Kazan Cathedral 12 3.2 Cathedral of St Isaac 14 3.3 Foundations and pavements 16 3.4 Monuments and ornaments 18 4 summary 21

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1 BACKGROUND AND AIMS 1.1 The historic center of St Petersburg According to UNESCO, St. Petersburg has an outstanding historical universal value. The city has preserved its historic appearance and beauty and its sites have been maintained and respecting not only the cultural landscape but also the smallest details. This requires large investments as well as good cooperation between the city, the province and the state. The Ministry of Culture, the Government of and Leningrad Oblast Government work together to preserve and protect the historical sites not only of St. Petersburg city center but of the wider region. This entity also involves choosing the right restoration methods and materials and shares information of the restoration activities. The old St. Petersburg Stock Exchange was built between 1805 and 1810. It is located on the eastern edge of Vasilyevsky island. The stock exchange was designed by the French architect Thomas de Tomon. Restoration is very tense in the St. Petersburg area and the stock exchange is a good example of the large‐scale financial investments required for restorations.

Figure 1. Restorations of the St. Petersburg Stock Exchange on the eastern edge of Vasilyevsky Island.

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1.2 NaStA‐project The aim of the NaStA‐project is to expand and strengthen the operating environment for SMEs by increasing knowledge about the use of natural stones and related business opportunities in the fields of cultural and historical heritage. The main measures of the project include studies on the demand for original natural stone resources in buildings and construction (restoration needs), as well as the availability of suitable material for restorations. This goal is supported by researching and classifying the types of stone used in historic buildings, as well as developing methods to make restoration materials less noticeable and functional with different surface treatments. 1.3 Origin of natural stone resources We already have a good knowledge of where the building stones of several valuable historic buildings were once excavated (Figure 2). In this project, we will find out more about this by using modern research methods. Once we know where the stones were originally excavated, it may be possible to produce restoration materials from the left‐over stones in the historic quarry, either as properly shaped pieces of stone or as repair mortar.

If the stone needed for restoration is not available from the original quarries, we will try to find operating quarries for which a similar stone is available. This procedure respects historical sites and demonstrates to both the general public and professionals that restoration must be carried out in a time‐sustainable manner and in order to preserve the authenticity of the sites.

Figure 2. The Pyterlahti quarry at Virolahti had hundreds of people at work. Quarrying stones required careful planning as well as stone quarrying skills. The quarry is now filled with water and smaller pieces of left‐over stones. Left picture by Auguste de Montferrand 1836. 1.4 Spectacular natural stone logistics and construction Loading, transporting, and erecting large brittle stone products require precise plans and versatile methods. The implementation of the whole can even be equated with the construction of pyramids. The successful completion of these massive and unique events in stone construction contributes to the value of St. Petersburg as a historic site (Figures 1‐2).

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Figure 3. Loading, transporting and construction of the as an example of work‐ and time‐intensive activity (Pictures Auguste de Montferrand 1836).

Figure 4. Eastern part of Gulf of Finland

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1.5 The Alexander Monument as an excellent example of skillful restoration The Alexander Monument contains the longest single stone monoliths in the world (25.6 m) and is a fine example of how this site has been maintained by restoring cracks in the stone so that traces of the restoration are even difficult to detect. This shows that it is worth investing time and money in restoration in all the old stone structures and buildings in the UNESCO World Heritage Site of St. Petersburg. Material choices and working methods must respect the original buildings in order to preserve the value and authenticity of the object.

Figure 5. The Alexander Column at was built between 1830 and 1834 and designed by the French architect Auguste de Montferrand. Restorations of the column (right picture) are almost not visible. 1.6 Sites of pre investigation The map in figure 6 shows the location of the main items in this report. We carried out this mapping in a short time in order to get an idea of the most common implementations and materials of the restoration methods. In the next step, we will conduct a more comprehensive survey and review the findings with those active in restoration and those in charge. In the same context, we present the available natural stone resources that can be utilized in restoration.

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Figure 6. Location of main sites of this report

1. The quay in front of Russian Academy of Arts 2. Lomonosova bridge 3. Griboyedov channel 4. Birzhevoy Promenade 5. First winter bridge 6. Kazan Cathedral 7. Cathedral of St Isaac 8. Bolshaya Morskaya street 9. Galernaya street 10. Beginning of Nevsky Prospect 11. Old St. Petersburg stock exchange 12. Alexander column

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2 BRIDGES, RIVER BANKS AND STREET CONSTRUCTION St. Petersburg was built in the 1700s and 1800s in an area of low topography where floods are common. No materials suitable for these wet conditions were available on site, of which stone is naturally the best and most durable material. The city was designed according to the views of , and this entity involved the construction of the banks of the Neva River, the construction of bridges and Venetian‐type canals. The stone materials for construction were transported primarily by water. 2.1 The quay in front of Russian Academy The pier with the Sphinxes is an exceptionally impressive site in front of the Imperial Academy of Arts. 3,300 years old Sphinxes were brought from Egypt to Russia in 1832 and the pier was completed in 1834. In other words, sphinxes are a concrete example not only of the durability and spectacularness of stone construction, but also of the professionalism of historical eras in stone processing and material selection. This pier area is an excellent example of how important it is to pay special attention to the holistic restoration of valuable historic sites. It also contains carefully selected restoration materials that do not stand out from the rest of the environment.

Figure 7. The quay in front of Imperial Academy of Arts in University Embankment at Vasilievsky island. The two sphinxes from Thebe, ancient Egypt (carved 3300 years ago) are guarding the site.

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Figure 8. Egyptian syenite is installed on top of rapakivi granite from Virolahti. There are some broken corners in the edge of the Egyptian syenite. These broken stone edges are related to the history of these monuments and therefore do not need to be repaired.

Figure 9. A darker colored mortar or a piece of stone planted in a stone wall would better suit the nature of the site (left picture). The image on the right shows a typical situation where it is possible to repair a broken corner of a stone wall by using the same stone for restoration as the original wall.

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2.2 Lomonosova bridge over river Fontanka. The Lomonosov Bridge was built in 1785‐1787 over the Fontanka River. The bridge is decorated with beautiful stone and metal work. The stone railings of the bridge have later been repaired with light gray rapakivi granite, the upper edges of which have been shaped to be rather modern angular.

Figure 10. Lomonosova bridge (constructed 1785‐87). The frame of the bridge is made of different shades of pyterlite rapakivi granite.

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Figure 11. Near the Lomonosova bridge are fence posts that are made out of different types of rapakivi granite.

Figure 12. Joining stone structures and metal parts is often problematic and can cause the stone to break and the metal parts to rust.

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2.3 Griboyedov channel next to Kazan Cathedral Construction of the Griboedov Canal began in 1739 to prevent the city from flooding. There are a lot of activities in the area as there are busy streets running through the area. Despite the busy traffic, the area is very picturesque and the proximity of Kazan Cathedral with its open surroundings makes it one of the key areas of St. Petersburg. The canal is lined with colorful houses and churches. Due to these characteristics, special attention should be paid to the restoration of this area, e.g. for authentic restoration material choices.

Figure 13. Griboyedov channel next to Kazan Cathedral. The channel embankment is originally made of rapakivi granite. Restoration of rapakivi granite the embankment has been made with limestone. The NaStA project aims to find the original stone types for objects like this or to show replacement materials that are as original as possible. 2.4 First winter bridge and Venetian landscape Zimnyaya Kanavka connects the Neva and Moika rivers and, thanks to the bridge, the Old Hermitage Theater and the Hermitage Theater with its magnificent Atlas statues. The bridge has been erected as “the First Winter Bridge.

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Figure 14. First winter bridge is located in a place where Milionnaya street goes over Zimnyaya Kanavka river. Damages in pyterlite rapakivi granite have been restored with light color concrete.

Figure 15. At the Birzhevoy Promenade damages of pyterlite rapakivi granite have been restored nicely with same type of stone.

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3 BUILDINGS, CHURCHES AND MONUMENTS St. Petersburg has a very diverse selection of magnificent churches of different sizes of different religions, utilizing a lot of stone. Public and private buildings and monuments are also large, merging with the harmonious architecture of St. Petersburg. 3.1 The Kazan Cathedral Kazan Cathedral is an Orthodox cathedral built in 1801–1811 along Nevsky Prospekt according to the plan of the architect Andrei Voronin, in the shape of a Latin cross. Kazan Cathedral is built mostly of Putilova limestone and Pudost travertine. Serdobol gray granite has been used mainly in the foundations, as well as some pyterlite rapakivi granite.

Figure 16. Kazan Cathedral on Nevsky Prospekt is the main church in St. Petersburg. The colonnade of the church is similar to that of the church in St. Peter's Square in Rome.

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Figure 17. The statue of field Marshall Mihail Kutuzov stands in the front of Kazan Cathedral.

Figure 18. The foundation of Kazan Cathedral has been successfully restored with the same type of stone (possibly Vozrozhdenie granite) as the foundations are. The color of the repair mortar could be a slightly darker. Similarly, the color of the Mihail Kutuzovs statue pedestal patch is not quite perfect.

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3.2 Cathedral of St Isaac The Orthodox Church of St. Isaac was built in 1818–1858. It is one of St. Petersburg's most significant attractions with its magnificent 120 granite columns and they have been excavated from Virolahti.

Figure 19. The double‐decker buses serve as the scale of the massive but beautiful St.Isaac Church.

Figure 20. Pylons, basement, stairs are made of pyterlite rapakivi granite, walls of Ruskeala marble.

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Figure 21. Rapakivi granite has been beautifully restored with the same type of stone at the bottom of the column. Restoration with Ruskeala marble has been treated with gray wax‐like substance. Long faults in the pylons are difficult to restore, here made succefully with reddish mortar.

Figure 22. One of gray walls made of Ruskeala marble has been treated with a wax‐like substance as a restoration test. The new color differs significantly from the original

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3.3 Foundations and pavements The design, repair and restoration of modern and historic sites often overlooks the aesthetic qualities of street construction. It is important to understand that foundation and paving stones play an important role, especially in the vicinity of historic buildings, and their restoration should be carried out with as much piety as the actual sites. If the streets are carelessly repaired, it will interfere with the formation of a harmonious overall picture.

Figure 23. The building of the General Staff of St. Petersburg was built in 1820–1830 as two separate buildings are connected with the triumphal arch symbol of victory in the war.

Figure 24. Next to the door rapakivi granite blocks have been replaced with gray granite.

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Figure 25. Galernaya street. Basement of the building constructed of rapakivi granite and other red granite. Rapakivi granite restored with other porfyric granite type.

Figure 26. Another basement where rapakivi granite has been restored quite nicely with similar looking granite.

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Figure 27. The door portal (pyterlite rapakivi granite) at the beginning of Nevsky Prospekt shows a very successful restoration with exactly the right type of stone used. The other image, with a gray granite replacement, is slightly different in color from the original. 3.4 Monuments and ornaments Repairing stone monuments and ornaments is very difficult. In St. Petersburg, this is not a big problem, because the ornamentation of St. Petersburg’s structures has been realized to a greater extent by metal, painting, and goldsmithing, for example. Of course, there are also many examples of decorative decorations such as the lower and upper parts of the statue of Alexander.

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Figure 28. Ornaments are challenging to restore. It is generally recommended not to use coarse‐ grained stones in highly decorative ornaments.

Figure 29. Repairs to the foundations of streets and houses should be carried out on a quick schedule, as this will prevent water from entering the structures to cause greater damage. Naturally, making these repairs is difficult and expensive, e.g. due to traffic problems caused by the repair work.

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Figure 30. Large pyterlite rapakivi granite pavement slabs have been replaced with darker granite.

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4 SUMMARY

 The St. Petersburg region has an excellent Coordination council that creates a framework for the protection and restoration of the historic St. Petersburg. The Ministry of Culture, the Government of Saint Petersburg and Leningrad Oblast Government work together to preserve and protect the historical sites not only of St. Petersburg city center, but also of the wider region. This entity also involves choosing the right restoration methods and materials, and shares information of the restoration activities.  The prevailing long‐term co‐operation between Russia and Finland in the stone research sector benefits both countries. Beneficiaries are also companies in the stone and tourism sectors.  As a result of our cooperation, we can show where authentic natural stone materials are available for restorations. In addition, we study restoration methods and materials that can be used to produce long‐lasting site‐respecting restorations.  In the vicinity of valuable historical sites, special attention must be paid from street level to the roof and to the environment as a whole. The design, repair and restoration of modern and historic sites often overlook the aesthetic qualities on the street level. It is important to understand that foundation and paving stones play an important role, and their restoration should be carried out with as much piety as the actual sites. If the streets are carelessly repaired, it will interfere with the formation of a harmonious overall picture.  This study exemplifies only a few objects. More comprehensive studies will be carried out later. The results of the surveys will be shared with various stakeholders so that the geological information can be utilized in the maintenance of the unique St. Petersburg.

Vorobyov Maxim 1835

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