Alright, here are my suggestions for the trade goods. I ended up filling the entire map, I obviously don't expect everything to be copied like that, but once I started suggesting some goods, then that necessarily meant some other goods had to move around.
When it comes to things like crops, I don't think you'll find many good sources for exactly how they were distributed anyway so it's pretty arbitrary.
I made a map with all the suggestions:
And here the details:
Gold, Silver, Tin, Lead, Copper, Saltpeter:
Not much in this area, just one location I would suggest.
Limbourg: Lead. There is a town called Bleyberg/Blieberg/So-on-Mont-d'-Plomb (meaning lead mountain) in the area, modern name
Plombières. While lead wasn't mined at the start of the game, mining was done throughout most of the games timespan. Since the Low Countries don't have a lot of mines other than coal and iron, I think it's the better good than just another lumber location.
Iron and Coal:
We are dealing with the most important iron ore location in Europe here, although it wasn't hugely important yet in the game's time period. The
Minette deposits' insane richness only really became relevant during industrialization, when large amounts of ore were needed for industrial steel production, but I think it's a waste not to give all the minette locations iron. They are famous for it and iron was produced in the area since Roman times. Belgium even exhausted its share of them by the mid 19th century.
For reference, I have roughly drawn the location of the Minette deposit on the map, sourced from
a 1921 report on iron ore reserves in Europe.
Thionville, Luxembourg, Arlon, Longeville(?) and Wallerfangen: My suggestion is iron for all of them. Thionville's coal should go to Saarbrücken instead. Wallerfangen could have coal as well, but I think iron was more important.
The region along the Meuse (so locations Mons, Wavre, Namur, Liège, Walcourt, Dinant and whatever that small font long name location next to it is) were one of the most industrialized regions in the world at the end of the game's timeframe, highly industrialized already around 1800. So there definitely should be some potential there.
Namur is shown to have marble production, but I think it should be iron. It became famous for its method of iron smelting, which was called the Walloon method
and spread as far as Sweden. Unless there is some specific reason for marble production there? Iron could be in Liège as well, but I don't think it needs to be that concentrated and alum seems fine for industrial production.
Mons is the location of the borinage coal field. Very rich, but how does the game model coal only being used as an alternative to firewood (which became quite expensive in some regions) for most of the time period? Until the puddling process and steam engines, there really isn't a special use for coal and those only happen in the 18th century.
I think
Mons, Wavre, Douai and Lens would be coal locations, but only later in the game. I don't believe coal here mattered before the inventions mentioned above.
Coal should also be present in
Maastricht and
Lommel later on. See
this map for coal locations in the Low Countries.
BTW, Arras is shown to have coal, but I don't know why. The coal is clearly further north.
We could really use some clarification on if coal is supposed to exist from the start or be added later in the game. If the latter, then there would only be few locations with coal at the start, maybe some in England, Saarland and the Ruhr area, were it was actually used as a replacement for firewood.
Alum and Mercury:
Pretty hard to find any sources for production of alum or similar materials, as they aren't as important as stuff like iron.
Alum in
Liège as a mining center of the period is fine, I think, especially since Flanders needs it. Most of the alum supply of the period was imported, though.
Doesn't look like there was any significant mercury production in the area.
Edit: After some more research on alum, it being produced in Liège is absolutely correct! It was only established 250 years into the game, but it was pretty important. I want to add that coal production actually was very important in Liège at the start of the game.
Pearls, Medicine, Amber:
Honestly I wouldn't really know what medicaments represents or why pearls are in the Low Countries. While I believe some amber can be found at the North Sea, it wasn't significant.
Clay and Sand:
It looks like the Netherlands do have some good clay resources, even after all the polder business, so they probably should have at least one location with clay. There are also old clay mines in Belgium around Kortrijk which gives its name to a geological formation that mainly consists of clay.
I suggest
Kortrijk,
s'-Hertogenbosch and
Cuijk for clay.
There is actually a 'desert' with sandy dunes south of s'-Hertogenbosch which was caused by excessive peat and clay extraction from the marshland in the area, so it's good that this location doesn't have farmlands vegetation. Peat mining was even outlawed in some areas, as it became too dangerous.
This begs the question: how will draining the marshland be represented in the game? You could start some of those marsh locations out with clay deposits, but if they are made into flatland, they could get rye and vegetables as resource.
North Brabant is generally very sandy in terms of geology, so maybe this is somewhere where sand production could happen?
Sand was widely available anyway, and the limiting factor for glass production was fuel, which is why glass was often made close to a forest. So sand is kind of a filler good.
I suggest sand for
Breda, Dunkirk, Dordrecht and Makkum.
Salt:
Zeeland, famous for its salt production for a long time, so
Middelburg having it is correct. Zeeuws-Vlaanderen, so
Hulst also produced salt. I don't think there should be too much salt production around, though, because Dutch traders actually sailed to Portugal to get salt from the famous Setubal deposit and sold it in Northern Europe. Maybe one more in
Dokkum, and that's it?
Marble and Stone:
I couldn't find any evidence for marble or alabaster in the Low Countries. I found a German article talking about a sculpture made from alabaster in the Low Countries, but the material was found to have been imported from Franconia through the Rhine and Main.
There is the Carrières du Hainaut quarry, which produces a certain type of limestone, but does that count as being special enough? If so, then
Mons should have marble, if not then stone.
Stone looks like another filler good mostly for hilly/mountainous locations. Not really a strength of the aptly named Low Countries.
Other than the
Mons location mentioned above, I suggest stone for
Oudenaarde and
the unreadable location north of Bastogne.
Dyes:
Madder was mentioned in this thread before. Definitely a dye that was extensively grown in the Low Countries. Zeeland should probably have salt, though, so I suggest dyes for
Rotterdam,
Den Haag and
Ghent.
Wine:
In my opinion, there shouldn't be wine here, as we're coming out of the warm period at the start of the game and making wine wasn't really viable for most of the game's timeframe in this region.
Fiber Crops and Wool:
I saw some people suggesting that there shouldn't be much wool production here, because they imported English wool. But there was still some domestic wool production, of course, and a lot of flax production as well. This production center for cloth just had THAT much demand.
For wool I would suggest
Thouin, Walcourt, Maastricht and Weert.
For flax (fiber crops) production I'd suggest
Sint Niklaas, Harderwijk, Doetinchem, Zuthpen and Enschede.
Rye (Sturdy Grains) and Wheat:
I know from international statistics published around 1900 that wheat production in the Netherlands was 22% of rye production, while for Belgium it was 61%, but I have no idea how accurately this translates to this game's time period. It does suggest to me that rye should be the predominant crop in this region.
So, for wheat I would suggest
Cassel, Ypres, Lille, Tournai, Douai, Valenciennes, Wavre, Verne, Brussels, Nijmegen and Arnhem.
For sturdy grains I would suggest
Utrecht, Apeldoorn, Deventer, Zwolle, Ostende, Leuven, Mechelen, Turnhout, Lommel, Maasmechelen, Hasselt and Eindhoven.
Horses
Now that's a filler good if I've ever seen one. You can have those anywhere where you have livestock, but I'd assume horses 'production' to be more common around population centers.
For horses I suggest
Antwerpen and Helmond
Lumber
Definitely something for the Ardennes. Not all that much lumber in the rest of the Low Countries.
I suggest
Venlo, Bouillon, Bastogne, St. Vith and Stavelot.
Wild Game
Also something for the forested Ardennes, but not much.
I suggest to keep it in
Neufchateau and replace the fur in
Wiltz
Fish
Mostly makes sense as a good for cities, in my opinion, since that's where the fishermen and their guilds would be,
So I suggest
Bruges, Leiden, Amsterdam, Alkmaar, Hoorn, Harlingen, Groningen and Appingedam.
Livestock
Should obviously be mostly in location that aren't that great for crops, but there is always going to be a certain mix.
I suggest
Dinant,
Gouda, Assen, Emmen, and Wedde.
Legumes
An alternative farming good, I don't think there are going to be any historical sources showing a significant differentiation between growing legumes and other crops, so again it's pretty arbitrary.
I suggest
Leeuwerden, Aalst and Coevorden.
