The Augustan era presents a period of prosperity that had rarely if ever been previously attained in human history. A massive standing army helped to keep the peace within Roman territory, while ambitious building projects flourished. As Rome became more proficient in the manufacture and use of cement, so too larger arches and vaults could be fashioned allowing buildings of a size never before dreamed of. This same material made it possible to build the walls of these structures faster and cheaper than ever. The results could be clad in a range of eye-catching stones, including marble, alabaster, basalt, and porphyry. Even today, we are amazed by the range of amenities and degree of refinement achieved: aqueducts, roads, bridges, venues for shows and games, baths with hot water where you could wash every day for a modest sum, latrines with running water, fountains on every block and drains in houses and streets, and huge paved squares with columns and statues of marble, if not bronze. In the homes of the wealthiest, there were underfloor heating systems, hot water taps, marble decoration, peristyles with columns and statues, tiles on the roofs, and glass or translucent sheets in the windows. It is only by appreciating this environment of luxury and refinement that the value attained by a type of rock known to the Romans as lapis specularis or ‘mirror rock’ can be fully grasped.
Exploring, finding, and measuring
In geological terms, lapis specularis is of evaporitic sedimentary origin and composed of gypsum that, in its pure form, is crystalline and even colourless. The rock has a tendency to split into parallel layers, while its hardness is low, meaning it can be scratched with a fingernail. According to the ancient author Pliny the Elder, the province of Hispania Citerior in Spain was the only source of this specular stone, which was extracted in a district that stretched for roughly a hundred miles around the city of Segóbriga. There, this valuable commodity was extracted from a network of shafts and galleries that descend to a considerable depth underground.
Although the location of this ancient mining district has long been known, no research has previously been conducted on its size and characteristics. As a consequence, the physical remnants of the Roman mining operations remain almost unknown. In order to address this, our aim is to explore the hundreds of galleries attested in the region, record them, and investigate the archaeology of extraction operations, in terms of both artefacts and tool marks. If this sounds like a simple task, nothing could be further from the truth. One complication is that almost all of the galleries are choked with rubble. It has traditionally been assumed that Roman miners routinely filled the workings they had already exhausted with debris from the new ones they were opening, as this involved much less labour than removing all of the material from the mine. As a result, it is often necessary to dig narrow holes through this mass of detritus in order to access new sections.
Rise of the elites