6 July 2025 The Future is the Product of the Past

Roman-era Mixers and Millstones Made with Geology in Mind

A study on stone tools from an outpost of the Roman Empire has found that for ancient bakers and millers, having the right tools was a matter of geology. 

A team of geoscientists and archaeologists made the discovery by analyzing samples of the tools at a University of Texas at Austin geology lab, finding that dough mixing vats and millstones from Roman-era ruins of Volubilis, a city in Morocco, were made from specific rock types that probably improved each tool’s function.

Furthermore, the researchers determined that the stones were sourced locally, a discovery that challenges a theory that some millstones had been imported from afar. It also means that the craftspeople who made the tools may have received input directly from the workers who used them. 

“It is interesting because it is a very local source and seemingly from one source,” said Jared Benton, a study co-author and an assistant professor at Old Dominion University who studies trade between Roman-era workshops. “One wonders if there’s not a group of bakers that are coming together and saying let’s buy our stuff from this one quarry, or maybe there’s just one guy who [sells the stones], and that’s it.”  

The results were published in the Journal of Archaeological Science: Reports

Derek Weller, a postdoctoral researcher at the University of Tokyo’s Earthquake Research Institute, led the study. Additional co-authors include Omero “Phil” Orlandini, research associate and manager of the Electron Microbeam Laboratory at the UT Jackson School of Geosciences; Lauren LoBue and Scott Culotta, both undergraduates at the Jackson School; and Christy Schirmer, a graduate student in UT’s Department of Classics.  

An olive millstone in Volubilis. Research assistant Drew Messing holds a tool for scale. Photo: Jared Benton.
An olive millstone in Volubilis. Research assistant Drew Messing holds a tool for scale. Photo: Jared Benton.

The study got its start in early 2020 when Schirmer showed up at Orlandini’s lab with a box of rocks. They were pieces of the stone tools that she and Benton had collected from the tools in Volubilis – and they were curious about were learning more about their geological makeup could lead them. 

“They sort of look the same when they’re in tool form, but as soon as we started looking, it was clear that they were completely different,” Orlandini said. 

Orlandini got LoBue and Culotta on the case. The undergraduates put all 16 samples through a detailed scientific workup to determine their composition at the geochemical level.  

Their research revealed a rock type for each tool type. Grain millstones were made from vesicular basalts (a volcanic stone full of sharp-edged pores); olive mills were made from clastic, fossiliferous limestone (a limestone containing fragments of other rocks and small fossil shells); and dough mixers were made from limestone with no clastic material or fossils.  

 The study notes how the rocks’ attributes relate to each tool’s function. For example, the pores in the basalt may have helped provide fresh edges that could help grind wheat into flour as the stone was worn down. 

 Weller also used the geochemical data to determine that all the stones came from sources near Volubilis. Limestone is plentiful in the region, and two limestone quarries were already known to be active during the Roman era near Volubilis. But archaeologists previously thought the basalt – which Weller found came from the nearby Middle Atlas Mountains – was imported from Italy.  

In addition, the research found that each rock type came from a single location rather than sourced from different places around Volubilis. Benton said this suggests that a single supplier for each stone type might have been meeting all demand in the city and getting input from local people.   

Elizabeth Fentress, an archaeologist specializing in Roman settlements in North Africa, said that the study is a great example of collaborative research.  

 “It is hardly the only collaboration between geologists and archaeologists, but an excellent one,” she said. “The key is, as here, that the archaeologists ask the right questions and use their knowledge to interpret the answers.”

THE UNIVERSITY OF TEXAS AT AUSTIN

Cover Photo: The ruins of Volubilis, a city in Morocco that was part of the Roman Empire. Photo: Sergio Morchon/ Flickr

Related Articles

Poseidon Temple in Greece Larger than Previously Assumed

27 January 2024

27 January 2024

New excavations at Kleidi-Samikon in Greece’s Western Peloponnese show that the temple, discovered in 2022, is more monumental than previously...

Archaeologists Discover Assyrian-Style Leather Armor 2,700 Years Old in China

11 December 2021

11 December 2021

The new research shows that the unique leather armor found in a horse rider’s tomb in Northwest China was made...

Archaeologists Discovered One of the Earliest Christian Buildings in Bahrain

14 July 2024

14 July 2024

Archaeologists have uncovered one of the earliest known Christian buildings in the Arabian Gulf, located in Samahij, Bahrain, and providing...

On a 5,300-year-old skull, archaeologists find evidence of the first known ear surgery

20 February 2022

20 February 2022

Humans may have begun performing ear surgery more than 5,000 years ago, say Spanish archaeologists. Spanish researchers say the skull...

Largest Anglo-Saxon cemetery discovered in Britain illuminates ‘Dark Ages’

16 June 2022

16 June 2022

Archaeologists working on HS2 (the purpose-built high-speed railway line) have discovered a rich Anglo-Saxon cemetery in Wendover, Buckinghamshire, where almost...

Imperial cult temple discovered in Spello: It opens a new chapter in the Roman Empire’s transition from paganism to Christianity

6 January 2024

6 January 2024

American researchers have announced the discovery of an Imperial cult temple in Spello, Italy. The discovery was announced by Douglas...

Archeologists in Peru find a 1,000-year-old adolescent mummy wrapped in bundle

25 April 2023

25 April 2023

Archaeologists have unearthed a more than 1,000-year-old mummy on the outskirts of Peru’s capital, Lima. The mummified adolescent was wrapped...

The Ephesus Massacre: 80,000 Romans Slaughtered in a Single Night of Blood and Betrayal

29 May 2025

29 May 2025

The Ephesus Massacre saw 80,000 or more Romans killed overnight during the Asiatic Vespers — one of the deadliest uprisings...

Sumatran fishing crews may have found the legendary Gold Island in the Mud of the Indonesian River

24 October 2021

24 October 2021

The site of the Srivijaya kingdom, known in ancient times as the Island of Gold, may have been found by...

5,000 years old Mother Goddess statuette unearthed in Yeşilova Mound

25 October 2023

25 October 2023

A Mother Goddess statuette, determined to be 5 thousand years old, was found during the excavations carried out in the...

1,400-year-old temple from the time of the East Anglian Kings discovered at Suffolk royal settlement

21 November 2023

21 November 2023

Archaeologists have uncovered a possibly pre-Christian temple from the time of the East Anglian Kings at Rendlesham, near Sutton Hoo...

40 Skeletons in Giant Jars Found in the Corsica Necropolis

16 May 2021

16 May 2021

Archaeologists working on the French island of Corsica discovered around 40 ancient graves where persons were buried inside gigantic jars...

Archaeologists unearth the Torah Ark of the Great Synagogue of Vilna, destroyed in Lithuania

30 August 2021

30 August 2021

In Vilnius, the capital of Lithuania, in excavation exposed the Torah ark and bimah (raised prayer platform) of the Great...

New finds in ancient Rome’s Pompeii show ‘conditions of precarity and poor hygiene, in which people of lower status lived during that time

20 August 2023

20 August 2023

Archaeologists have discovered a small bedroom in Civita Giuliana villa near Pompeii that was almost certainly used by slaves, throwing...

Puzzling rings may be finger loops from prehistoric weapon systems

24 May 2023

24 May 2023

When many researchers looked at an astonishing group of artifacts discovered at French archaeological sites, they presumed they were ornaments...