Learn Swedish: Gruvan är gammal. Därtill är fyndigheten nästan tom. - The mine is old. Moreover, the deposit is almost empty.

Därtill acts as an adverb at the beginning of the clause. In Swedish, the main verb must almost always come in the second position (the V2 rule). Since därtill takes up the first position, the verb är comes second, pushing the subject fyndigheten to the third position.

How formal is därtill compared to other words for "moreover" or "additionally"?

Därtill is quite formal and is generally used in written Swedish, news reports, or formal speech. In everyday conversation, you would be much more likely to hear dessutom (besides/moreover) or simply just add också (also) later in the sentence.

What is the root of the word fyndigheten?

It comes from ett fynd, which means a find or a discovery. By adding the suffix -ighet, it becomes en fyndighet, which in this context refers to a natural resource deposit, like ore or minerals in a mine. The -en at the end makes it definite (the deposit).

Why does the sentence use tom instead of tomt?