Gold
Gold and Galaxia General Mineral Information:
Gold is a rare metal that is also an element (on the periodic table of elements). Gold ranges from a rich yellow hue but can also be found faded down to white, pale yellow, or even a coppery pinkish yellow. Gold is one of the most historically sought after metals and is used as a standard to measure international currency. It is highly useful in medical equipment, electronics, as well as uses in jewelry. There are many, many legends of people going mad or meeting some other calamity in pursuit of a gold treasure.

Other Properties:
Typically believed to draw its power from the sun, gold is most often used to amplify energy. Gold can help to prevent spiritual decay and it can clear negativity. It is also sometimes used in combination with precious stones for a better charm - Topaz in a Gold setting can disperse enchantments, while rubies set in gold can refresh the body. Gold also, unfortunately, has a propensity to bring greed into the soul. Pink gold represents spirituality, while white gold can combine both the sun and the moon's energies.

Notations on Gold:
It is associated with the 50th anniversary in western culture (The "golden anniversary"). It is also associated with the Fire Element.

Links between Gold and Golden Queen Galaxia:
Gold is an extremely rare metal with many useful capabilities- especially being versatile in amplifying the skill of others. Golden Queen Galaxia is also like this, but has most notably the one caveat associated with gold as well- immense greed. In both the anime and manga (and even the musicals) Galaxia is a soldier who has been corrupted and is collecting something, despite the tremendous cost to others. In the manga, she collects Sailor Crystals to increase her own power, and places them in a garden selfishly destroying the lives of the other Sailor senshi in the process. In the anime, Galaxia is collecting the special starseeds of the Sailor senshi, also at the cost of their lives.

References:
Gold and Spirituality
Gold