There sure is a lot to say about our powerful, fiery friend of action, Mars... So this is definitely an abridging of all his associations!
Mars is best known as the god of war, and the planetary namesake certainly embodies some of those properties: Action, conflict, desire, passion... these are all influences of Mars.
In your natal astrology chart, Mars is where we look for how you motivate yourself, deal with conflict, and advocate for yourself and others.
Ruling over Aries, Mars is fire all the way down. He's combustible but not necessarily combative - it all depends on the context.
Classically, Mars was known to rule over Scorpio for his fixed quality, emotionality, and interest in life/death cycles - Scorpio is very Martian despite being a water sign! (Scorpio is now considered ruled by Pluto but the affinity remains.)
As for crystals, Mars responds to pretty much everything red! Rubies, rhodochrosite, watermelon tourmaline... and so many more.
In addition, citrine, onyx, and diamond have been known to channel Martian energy - mainly because of their own action-based, "make things happen" properties.
In tarot, The Devil, The Emperor, and The Tower cards are all associated with Mars. Why? Think masculine (or yang) energy, think necessary force, think endings that lead to new beginnings... Like fire itself, it seems (or is) destructive in the moment, but ultimately is a cleanse.
In herbs and plants, Mars can be associated with basil, garlic, snapdragon, honeysuckle, and so many more. They are all powerful flavors or flowers, as well as healers in their own uses. Often these plants will be used in offerings to Mars because of their potency!
Here's a graphic for quick reference:
