vein
The word 'filón' in Spanish is primarily used in the context of geology, referring to a vein or deposit of valuable minerals in the earth. In a broader sense, it can metaphorically refer to a rich source or valuable find of any kind, not necessarily related to geology. Hence, offering a single English equivalent is complex. Depending on the context, it can be translated as 'lode', 'bonanza' or simply 'gold mine'. The correct interpretation largely depends on its usage in a sentence.
This business is a gold mine.
In this context, 'filón' refers to a profitable source or a very good opportunity, which is similar to the English expression 'gold mine'.
That author is a gold mine for publishers.
Here, 'filón' is used to convey that the author is a valuable and profitable source for publishers, much like a 'gold mine' in English.
This idea is an inexhaustible vein.
In this example, 'filón' is likening the idea to an 'inexhaustible vein' that keeps producing or yielding benefits. The term is often used to describe a situation or thing that is very productive or beneficial.