WI: The Rock of Tolfa... and the Alunite Crusade?

This is not the beginning of a timeline, but I've always found this to be an interesting potential POD and I thought I'd see what you might make of it. And hey, who doesn't like a little economic history?

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This is Alunite.

tIbEIuN.jpg

As it happens, there is a lot of it in the hills around Tolfa, about 35 miles northwest of Rome.

Alunite is so named because you can make Alum from it. Alum – specifically, potassium aluminum sulfate – is used for a range of industrial and commercial purposes today. It’s the primary ingredient in the styptic pencil which I keep by my sink in case I cut myself shaving.

In the Middle Ages, the most important use of alum was as a mordant for dye. Wool is not always easy to dye – some dyes “stick” to cloth very easily, but others do not. A mordant is an additive that helps the dye stick. A number of different mordants were used in the medieval period, from copper to human urine, but the best one by far was alum.

Unfortunately, good alum came only from the east. Some came from Anatolia, a smaller amount from Spain, but most of it came from Egypt, where alum can be found in a pure natural form that needs practically no further refining. For much of the Medieval period, Christian Europe was, in the context of international trade, known for its wool – European merchants and nobility wanted all kinds of things from the east, but to settle the trade balance they counted in substantial part on woolens exported from places like Flanders and Lombardy. Cloth becomes much more valuable when dyed, of course, but to get that, they needed to trade with Egypt or the Byzantines (or later, the Ottomans).

So why not use the alunite of Tolfa? Well, because until the 15th century, Europeans were unaware that the rather unimpressive rock of Tolfa could be used to make alum.

Enter Giovanni di Castro. Giovanni was an Italian dyer working in Constantinople. Fortunately for him, the process by which alunite was made into alum was known to the Greeks, and thus known to Giovanni; unfortunately for him, the 1450s was not the ideal decade to be running a business in Constantinople. Following the city’s fall to the Turks, Giovanni lost everything and went back to the home country. But in 1461, in the hills near Tolfa, he noticed a rock that rather reminded him of the stone the Greeks used to make alum, and reported his discovery to Pope Pius II.

For Pius, this was nothing less than a miracle. By that time alum was mostly bought from the Turks, who Pius viewed as an existential threat to all Christian civilization. The emerging industry, which was placed into the hands of the Medici to manage, yielded something roughly on the order of a hundred thousand ducats annually. The Papal States, throughout much of the middle ages an economic backwater, now controlled a resource all of Europe desired, and an impressive amount of it - the mines produced up to 1,500 tons of alum a year (alum, mind you, not alunite) and produced nearly half a million tons of alum over the course of the ~360 years of operation following the initial discovery.

Pius had big dreams – he wanted to create an enduring monopoly to finance a crusade against the Turks. His successor, Paul II, went so far as to forbid Christians from buying their alum elsewhere. By the late 15th century, however, the crusading spirit was dead and buried, and the Pope no longer had the influence he once did. Agostino Chigi, who eventually became manager of Rome’s alum, tried to enforce Rome’s strict monopoly, but his stranglehold on the supply and his insistence on high prices made many enemies and encouraged states like Venice to thumb their noses at the Pope and buy alum from the Turks anyway. It was not long before new techniques for getting alum out of shale were developed in England and spread elsewhere.

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There’s at least a shred of plausibility to an earlier Alunite discovery at Tolfa. After all, Giovanni didn’t discover the process, he just brought it west after Constantinople’s fall. All you need is someone as perceptive as Giovanni who is familiar with the industry and able to make the same trip he did, from the New Rome (or at least its territories) to the old.

The weathering of Alunite to produce Alum was described in the (presumably) late 10th century Arabic work known in Latin as "De Aluminibus," possibly written by the Andalusian Al-Majriti. De Aluminibus seems to have been translated into Latin in the 12th century. That description is of a laboratory process rather than an industrial one, but the basic procedure of crushing, roasting, and soaking is essentially the same.

As an industrial process, the earliest I can trace it is to a mention of highly productive “alum mines” at Phocaea – a location rich in alunite deposits – being given by the Byzantine emperor to the authority of Genoese merchants in 1262. That, then, is the earliest point I know of where you could get a proto-Giovanni with certainty: you have Italians (more specifically, Genoese) in charge of the Phocaean alum monopoly, who are in a direct position to observe the process and could conceivably travel to Rome and its environs. Obviously, however, alunite mining and refining must have been known and practiced before then - possibly long before - and likewise Italian merchants had been heavily involved in the commerce of the empire long before 1262.

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So what can we do with an alum monopoly in an earlier age (for the sake of argument, let’s restrict ourselves to the 12th and 13th centuries), when Papal authority is stronger and the will to defy him weaker? What can a suddenly-wealthy Papacy accomplish? Launch a new alum-funded crusade, as Pius dreamt of? Fund opposition the HRE? Pay the Fourth Crusade’s debts and get it back on the rails? Or would that source of wealth be too irresistible a target to the Pope’s regional foes or the maritime republics for Rome to maintain control of it? Would a papal embargo on “infidel” alum be any more effective in the 12th/13th centuries than it was in the 15th/16th?
 
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