Granite: This rock is awesome

The ancient Egyptians carved their obelisks out of it, Goethe considered it to be a primary rock and today we often just trample on it carelessly. On the history and geology of granite.

Photo Lucas Bäuml

This rock is awesome

By ULF VON RAUCHHAUPT

Photo Lucas Bäuml

January 22, 2023 · The ancient Egyptians carved their obelisks out of it, Goethe considered it to be primary rock and today we often just trample on it carelessly.

On the history and geology of granite.

Dusty grey, mouse grey, ash grey.

There is also a stone gray in the fabric sample folder that Loriot presented to the Melzer couple as interior decorator Paul Winkelmann in the film "Ödipussi" from 1988, although the color was already quite fixed: Ms. Melzer finally decides: "We'll take the ash gray."

Granite gray was missing from Herr Winkelmann's palette.

However, this is not necessarily suitable for fabric sample portfolios.

The diversity of the interplay of dark mica with milky grey, semi-translucent quartz and light-colored feldspars is too great.

These three mineral groups make up all granites, and the particularly potassium-rich feldspars of some deposits can blend shades of gray with a variety of reds and pinks.

Around the town of Hauzenberg in the southern Bavarian Forest, the granite is actually only gray - but how!

A museum is dedicated to the stone in a quarry in which the light Hauzenberg granite and a slightly darker granodiorite were mined until 1980.

"The occurrence here would definitely have been further minable," says the museum director Ludwig Bauer.

"But there was trouble with the residential development all around." The region is now the largest active granite mining area in Germany.

Ten quarries are still active and cut a total of 300,000 square meters a year.

Hauzenberger granite from the Bavarian Forest, here in the form of a paving stone with an edge length of about eight centimetres.

However, paving granite often comes from China today.

Photos Lucas Bäuml

Why Bauer specifies stone production in square meters instead of tons or cubic meters becomes clear when you look up at the walls of the small museum café, whose floor was sawn out of the rock with diamond-studded ropes.

The enchanting decor of polished granite is the main reason why the quarries in the Bavarian Forest are still in operation.

The particularly pressure-resistant, abrasion-resistant and acid-resistant rock literally surrounds us at every turn.

Although not everything that is offered for sale in the building materials trade under the name of granite is actually granite.

For example, "Belgian Granite" is actually a limestone.

The curbs and cobblestones in our cities, on the other hand, are often made of real granite, but since the 1980s they have mainly come from China.

In the past, says Ludwig Bauer, granite was also quarried elsewhere in Germany, for example in the Upper Palatinate or in Lusatia.

“After sea freight became so cheap, we didn't stand a chance.

But the customer or the public sector must know: If you take stone from the Far East, you produce 72 cubic meters of greenhouse gas per square meter.” Together, fifteen stone carriers emitted more carbon dioxide than all 760 million passenger cars worldwide.

In the meantime, domestic granite has better chances again.

"But after we were harassed with Far East prices for 40 years, the problem now is getting staff." A hundred years ago, more than 12,000 people made their living from granite in the Hauzenberg region,

Granodiorite is very similar to granite.

In its feldspar content, however, there is significantly more calcium-rich plagioclase.

This sample also comes from Hauzenberg near Passau.

Photos Lucas Bäuml

German national rock

Even if Bavarian granite has been used since the late Middle Ages, it only began to be quarried more than just on the surface in the course of industrialization and after the Napoleonic Wars.

On the one hand, better steel was now available for its processing, and on the other hand, the demand for representative building blocks increased in the newly founded Kingdom of Bavaria.

Granite was also often used in the post-Napoleonic monuments that were springing up everywhere, such as the Liberation Hall in Kehlheim.

"He was raised to a kind of German national rock," says Ludwig Bauer.

In Prussia, for example, people were very proud of the Markgrafensteine, two large boulders near Fürstenwalde on the Spree.

This did not prevent a piece from the larger Markgrafenstein being split off in 1827 in order to make the huge granite bowl out of it.

which can still be seen today in Berlin's Lustgarten.

The fact that the margrave stones actually come from Sweden and only reached Brandenburg with the Ice Age glaciers was not known and would probably have been reluctant to acknowledge.

Scandinavian migration background: The large granite bowl in Berlin's Lustgarten Photo Picture Alliance

"Ask why did God make the precious stone so small and why so huge the granite /

Because God meant that man should regard it as more precious."

These verses were carved by the Scottish poet Robert Burns in 1791 on an inn window.

Yet the rock had only just come into its own, as Burns might know.

He had probably met the geologist James Hutton in Edinburgh in 1787, who two years earlier had made an epochal observation in Glen Tilt, a valley in central Scotland.

He had noticed red granite there, which cuts through the layers of sedimentary gray sedimentary rock in veins and veins.

The granite must therefore have formed later than the sediment.

But that was completely unheard of.

At that time, granite was considered one of the earliest rocks, if not the earliest, and this may have contributed to its career as Germany's national rock.

The mineralogist Abraham Gottlob Werner, for example, who had been a professor at the Bergakademie Freiberg since 1775, regarded it as one of the main components of the "primordial mountains".

After all, traces of organisms are never found in granite or similar "crystalline" rocks, which is why they must have been deposited in the earliest times, before life existed.

Werner believed that he had reason to assume that all rocks were deposits from the oceans.

Johann Wolfgang von Goethe also adhered to this idea, known as “Neptunism”.

He was not only interested in rocks as Mining Minister of the Duchy of Saxe-Weimar-Eisenach.

In 1784, the year before Hutton's discovery in Glen Tilt, Goethe wrote a paper

"About the granite"

, where he processed his encounters with the rock in the Harz Mountains.

Sitting on a high bare peak

," he writes there, "

and looking out over a wide area, I can say to myself: Here you are resting directly on a bottom that reaches down to the deepest places on earth, no recent layer, no piled up washed together Debris has come between you and the solid surface of the primeval world.
.
.

This is probably a reminiscence of the granite peak of the Brocken.

For Goethe, granite was the primary rock - but not only in the sense of the geological sequence, but also as the rock form from which all others are derived, as the primeval type of everything made of stone, analogous to his idea of a primeval plant, which was documented somewhat later.

But as James Hutton has shown, the great poet was horribly wrong here, both chronologically and geologically.

The appreciation of granite demanded by Robert Burns had only just begun at the time, or more precisely, had started again.

Because for a long time no one was interested in him - just like in the variety of shapes of the stones.

This may also have been due to the fact that the extremely influential Aristotle and other ancient authors only dealt with the topic marginally.

In any case, granite did not receive its name in the major European languages until the time of Goethe, derived from the Italian "granito" for "grained".

The word itself first appeared around the year 1500 among Italian stonemasons.

Magic of rose granite

It is perhaps no coincidence that this is exactly the time when the antique-loving Renaissance master builders in Rome used granite columns from antiquity again for a short period of about 30 years.

Previously, antique-style columns were mainly made of travertine.

Because granite was simply too hard for the early modern stonemasons - and even more so for the medieval ones.

Antique architectural elements made of granite were recycled for a good millennium from late antiquity onwards, but hardly anything could be changed about them - at most monolithic columns were sawed into disks.

Granite surfaces harden over time when exposed to air, so quarrying new material is easier than processing recycled rock.

Nevertheless, the Roman-era granite pits on Elba or Giglio continued to be used locally and to a limited extent in the Middle Ages.

Like so many other things, knowledge of the professional mining and processing of hard rock was lost in the West sometime in the fourth or fifth century.

The handling of granite was perfected long before the Romans, who decorated their forums, temples and thermal baths on the Tiber alone with thousands upon thousands of granite columns, some of them gigantic in size.

Very many of them came from Egypt.

Granite processing was already mastered there at the dawn of the Pharaohs at a level that was not reached again until modern times.

Granite is called "mātj" in Egyptian and is written with a hieroglyph as a so-called determinative, which represents a jug.

In fact, as early as the early third millennium BC, vessels of perfect quality were being made from various types of hard stone along the Nile.

The granite jar hieroglyph is also found in the place name "Abu" - that's what the Egyptians called the island of Elephantine opposite modern-day Aswan,

which was called Syene by the Greeks and Romans.

To the south, a 20 square kilometer outcrop of gneisses and granite begins.

All the granite for the temples, statues and obelisks of the Pharaohs came from here.

Up until the beginning of Roman rule over Egypt, an estimated 220,000 cubic meters of granite were quarried off Aswan, and again a multiple of this amount in the Roman Empire.

And here - only here - there is also the famous rose granite, often called syenite by the Romans, whose stunningly decorative color comes from potassium-rich feldspar.

Up until the beginning of Roman rule over Egypt, an estimated 220,000 cubic meters of granite were quarried off Aswan, and again a multiple of this amount in the Roman Empire.

And here - only here - there is also the famous rose granite, often called syenite by the Romans, whose stunningly decorative color comes from potassium-rich feldspar.

Up until the beginning of Roman rule over Egypt, an estimated 220,000 cubic meters of granite were quarried off Aswan, and again a multiple of this amount in the Roman Empire.

And here - only here - there is also the famous rose granite, often called syenite by the Romans, whose stunningly decorative color comes from potassium-rich feldspar.

Rose granite from the ancient quarries south of Aswan in Upper Egypt.

A high proportion of potassium feldspars gives it its characteristic color.

Photos Lucas Bäuml

The durability of granite was already legendary in antiquity.

Pliny the Elder writes about AD 70 about the mortuary temple of Pharaoh Amenemhet III, which was more than 1800 years old.

at Hawara in northern Egypt: “It has an entrance of stones and pillars of Parian marble.

Otherwise, it is made of blocks of syenite, which even centuries cannot destroy, even with the people of Herakleopolis, who, amazingly, view the structure with hatred.”

So if neither time nor vandalism could do much to the granite, one wonders how the ancient stonemasons managed to shape it.

For the time of the Romans and the Ptolemaic kings over Egypt, this is not quite so puzzling.

At that time, iron chisels were already available that could be sufficiently hardened using special techniques.

But two of the three millennia that Egyptian civilization worked with granite fell into the Bronze Age.

However, the rose granite that Pliny calls syenite has a hardness of seven on the scale of the Goethe-era mineralogist Friedrich Mohs.

Materials with a Mohs hardness of one are softer than a human fingernail, and those with a Mohs hardness of 10 are as hard as diamond.

Degree of hardness seven is far too hard for the copper chisels,

with which the pyramid builders shaped their blocks of limestone.

Copper has a Mohs hardness of three, and even tin bronzes containing antimony are not significantly harder.

Nevertheless, it is not necessary to bring in Atlanteans or extraterrestrials for the explanation.

The roughly spherical chunks of dolerite that were found in large quantities in the Aswan mining area, but also elsewhere in Egypt, are sufficient.

Dolerite is a type of basalt that has infiltrated fissures in the Aswan granite complex and solidified just below the surface.

The dark rock therefore runs through the area in narrow passages and breaks into sharp-edged chunks when it is weathered out.

The Egyptians used these to work the granite until they were rounded into balls.

Dolerite is as hard as granite and therefore wears out as a tool about as quickly as it removes the material.

However, experiments have shown

that a skilled worker could chip off a good twelve cubic centimeters of granite a minute with such dolerite hammers.

Projects such as the obelisk that can still be seen in the rose granite quarries south of Aswan were able to be realized with sufficient personnel deployment.

With a length of almost 42 meters and a base diameter of 4.4 meters, it would have become the tallest of all obelisks and at 1100 tons the heaviest monolith ever transported in ancient Egypt.

But 130 workers carved it out of the rock with dolerite hammers within a year.

It is not known why it remained unfinished, whether there were technical problems with transport or rather political and dynastic ones.

which can still be seen today in the rose granite quarries south of Aswan.