I suggest chrysophilia, which Wiktionary lists as meaning "The love of gold".

You were on the right track with aurumphilia, but there were a couple things to change. One is that "auri-" is the prefix form of the Latin word "aurum". The other is that there's some tendency to discourage mixing Latin prefixes with Greek suffixes, so you'd want the Greek prefix, "chryso-".

Notes: There were two points in the comments I want to address.

1. Edwin Ashworth pointed out that you can mix Latin and Greek roots, like in television. That's right. I was being overly grouchy and pushing one of my pet peeves. There are a lot of very serious words that mix Latin and Greek.
2. Toothrot pointed out a dictionary that lists chrysophilia as a sexual interest in gold and the color gold. It might be good to avoid this term if it has one definition that's so far from what you want. The suffix "-philia" often has a sexual connotation.

How about auriphilia or aurophilia?

From Wiktionary, the prefix aur-, which means gold, usually concatenates with -i-, hence my initial use of auri-.

Also from Wiktionary, -philia is used to form nouns meaning liking, love (for something).

Aurophilia is a related possibility. I found a number of links to it, e.g., related to artisans who produce fine works in gold and market them to those who love such works, aurophiliacs.

The correct answer is just

"gold bug"

as already given immediately in the first comment.

(Note that like many terms, it can be pejorative, or, perfectly neutral.)

Note - as suggested in comments

• gold mania

• gold fever

are highly-used terms.

In English, we use the term 'gold fever' both literally for a gold rush and metaphorically in literature for a personal or social infatuation with gold.

https://www.merriam-webster.com/dictionary/gold%20fever

Example: When the bank robber, who had planned to make away only with the contents of the registers to avoid the police, saw the vault filled with gold bullion, he was overcome with gold fever and dropped that he was carrying.

You could create a neologism, but this is rather well-recognized

I would say gold fever would be appropriate

Two other answerers have posted it after a comment by user Decapitated Soul but I think the proper way to post someone else's comment as an answer is to make it a community wiki.

Gold fever:
Noun
gold fever (countable and uncountable, plural gold fevers)

(literally) A feverish obsession with seeking gold ore.

[Wikitionary]

Dragon sickness.

Given that we're talking about dwarves, we could pull from the works of Tolkien and diagnose them with "dragon sickness" that afflicted certain dwarves in his works, as they became obsessed with gold and treasure, much like dragons do. This is an old mythological trope dating back to medieval Europe, with examples like the dwarf Fafnir physically transforming into a dragon as a result of his gold-lust.

"Gold-lust" or "gold lust" is another viable word/phrase to describe it, as well, which is less rooted in one particular author's work.

I am a supporter of the suggestion Auromania, but would like to offer some related suggestion as well:

auropathy Gold "sickness" - it would fit with a tendency of the medical profession to add "-pathy" or "-pathic" after anything to signify a sickness

auritis gold... "infection"

One small comment to add - often in these situations we think of Midas who loved gold so much that, when he was granted a wish, he asked that everything he touched would turn to gold. He was very happy until he wanted to eat some food or drink some wine...

Doctor Sebastian has diagnosed these Dwarves as suffering from a severe case of Midas disease.

Midas disease is not really a well used term in English, but is the title of a song by DEMONS & WIZARDS.

This should not be confused with the 'Midas touch', which generally means that everything you work on (or 'touch') turns out well (or 'gold'). For example,

She really seems to have the Midas touch.

neologism: Midamania - from Midas, with the S clipped or elided for euphony (or should that be euglossia, beneglossia, or proglossia? All neologisms for ease of speech.).