Crystals

The Crystals are extremely powerful objects imbued with cosmic magic that started forming in Wynn and Gavel after the meteors crashed in these provinces. Due to their place of origin, they have some unique mystical properties that are also shared with meteors: namely, twisting minds and sometimes even physical forms, as shown with the Gerts, which are villagers that were twisted by meteors beyond recognition. Another mystical property possessed by both Meteors and Crystals is the ability to extend lifespans. The Silent Expanse mountains that border Wynn are packed with these crystals due to the fact that, during the era of the Olm, this mountain range was constantly bombarded by meteors.

History
The Crystals have been known to exist at least since 1400 BP, as that is when the Gylia Cataclysm occurred, where the two Purple and Blue meteors crashed into the Gylia Plains and formed Lake Gylia, forming crystals around the area as well. The lake's crystal magic has also created Weirds around the area and affected an underground species of lake dwellers in a way that increased their lifespan and gave them intelligence. Around this time the Power Crystals have also been known to exist.

At an unknown time, the Olm used the power of the Crystals to escape Dern and flee to the Dernel Jungle to found the Ancient City. However, the overwhelming power drove them insane and led them to believe that the Dern Beast was calling them back to its realm. Some fell to the insanity, others to Corruption. The Olm had later hidden the Leaf Crystal near the Ancient City before it fell into ruins.

In 800 BP a mining team from Fruma uncovered crystals in what is today the entrance to the Silent Expanse while they were digging for emeralds, but they were quickly hidden away again in fear of their power.

Around 500 AP, during the time of the Twains, the Purple Crystal was hidden by them next to their mansion and was not uncovered again until WynnExcavation started digging there, long after the era of the Twains.

Around 970 AP, the company known as GavelExcavation moved their base of operations to Wynn after research on the Lake Gylia meteors ground to a halt. They had heard of crystals existing in Wynn and started digging around sites where Crystals were rumored to be, although some sites (for example, Site E) were abandoned after it was discovered they didn't contain any crystals. At the head of this new company, called WynnExcavation, was Amadel.

Power Crystals
Arguably the most famous of these crystals are the Power Crystals, exceptionally strong crystals that were hidden across the Wynn Province over hundreds of years by various civilizations. These Crystals were sought out by WynnExcavation after they discovered their existence in the province. It's rumoured (and later confirmed) that being in possession of all four of the Power Crystals could grant anyone the "ultimate power". Even more powerful than the crystals themselves are their Shards, which are supposedly only wieldable by people of a pure heart.

Yellow Crystal
The Yellow Crystal is the first of the Power Crystals, found in WynnExcavation Site A. It's the first Crystal that the WynnExcavation company dug up, in the middle of some ancient ruins. It may have been initially hidden by the Pharaohs of the desert.

Purple Crystal
The Purple Crystal is the second of the Power Crystals, found in WynnExcavation Site B. It was dug up by WynnExcavation next to the House of Twain. The fact that no original Twain was still alive after Mael Twain's death made it easier to excavate the Crystal. The Crystal itself was likely hidden by the Twains, although whether they had any connections to the Crystal is unknown.

Red Crystal
The Red Crystal, also known as the Fire Crystal, is the third of the Power Crystals, found in WynnExcavation Site C. It was dug up by WynnExcavation in the core of the Volcanic Isles and seems to have magical fire properties. It is likely that the Volcanic Isles themselves were formed by the Fire Crystal's magic. The identity of the people who hid it is unknown (if it was even hidden at all).

Green Crystal
The Green Crystal, also known as the Leaf Crystal, is the last of the Power Crystals, found in WynnExcavation Site D. It was dug up by WynnExcavation below an ancient temple in the Dernel Jungle near the Ancient City, of Olmic origins. This crystal was presumably hidden by the Olm after they went insane due to the Crystals' overwhelming power.

Other Crystals
There are other Crystals, besides the Power Crystals, scattered across the world that serve diverse purposes, although some of them aren't quite clear yet. Those that are worthy of mentioning are:

Tower of Ascension Crystal
The main defining feature of the Tower of Ascension, this crystal is powerful enough to make someone viewing it from afar dizzy. The reason the Tower of Ascension was built around it is unclear, though it is known that this crystal is the one responsible for the strange ice spike formations around the Ice Canyon, as well as the unique enemies that spawn in this region that are unique to it. The Death sitting atop the Tower presumably went insane and on a rampage due to the Crystal's influence.

Pink Crystal
Located in a cave with camps and unknown ruins, this Pink Crystal stands out as the only one of its color known in the world. However, its effects are unknown, as are its magical properties.

Void Crystals
These Crystals are scattered all around the Void and come in different sizes, although their colors (black and purple) are always the same. They also bear a striking resemblance to the Tower of Ascension Crystal. However, their effects and magical properties are unknown.

Trivia

 * Before the Gavel Reborn Update, Amadel says in WynnExcavation Site C that the Power Crystals were "hidden by four individuals who inhabited a mansion a long time ago", hinting at the Twains. After the update this was changed to "hidden by various civilizations over hundreds of years".