Learn Portuguese (Portugal): A joalharia fechou, de forma que o ourives não fundiu o ouro. - The jewelry store closed, so the goldsmith did not melt the gold.

The phrase de forma que can trigger either the indicative or the subjunctive depending on its meaning. Here, it describes a factual consequence of the jewelry store closing. Because it is an actual result that happened, we use the indicative (fundiu). If it described an intended purpose, it would require the subjunctive.

Would the meaning change if we used the subjunctive (fundisse) instead?

Yes, drastically! If the sentence were A joalharia fechou, de forma que o ourives não fundisse o ouro, it would mean the store closed on purpose to prevent the goldsmith from melting the gold. The subjunctive shifts de forma que from expressing a factual result to an intended goal.

Can I use de modo que instead of de forma que in this sentence?

Absolutely. de modo que and de forma que are perfectly interchangeable here and follow the exact same rules for choosing between the indicative and subjunctive moods.

What exactly is an ourives compared to a joalharia?

joalharia refers to the jewelry store itself or the jewelry trade, while an ourives is the artisan: a goldsmith or silversmith. The word ourives has roots in the word ouro (gold), but applies to artisans working with various precious metals.