Lightning souls

A storm is near, I can taste it in the air.. Make sure the tools are ready for harvest tomorrow, wouldn't want to miss out on those Lightning souls.

— A resident in Irai

Lightning in itself is a super powerful resource and would be great for loads of things if they weren't super unpredictable. But even harvesting a small percentage of the energy created in lightning is still a large amount compared to other energy resources.
People of Aewyn takes advantage of lightning storms and makes sure to know when and where it will hit, and they do this for one reason only: Lightning souls.

What is it?

An immense amount of energy is stored in a single lightning strike, so when they strike sandy grounds, the sand melts instantaneously and forms an exact copy of the lightning at the moment it hit. These are what Aewynians refers to as Lightning souls as it almost looks like the souls have been pulled out of them by the sand.
They only occur where there is sand in the top layers on the ground, and most places that meet these requirements are public areas. After a big storm, the dunes are littered with people digging and scraping away sand to find souls. They can be hard to spot, and it doesn't leave an impression on the top sand - only when you dig around one you are able to feel a sudden hard structure in the soft sand.

Great, but what do you use them for?

Most farmers and other workers have no use for such immense power, and their main motivation for searching for them is to make a profit. Larger organizations, weapon-smiths and potion makers are typically the ones looking to buy souls.
Another important purpose of the souls is to have a source of light when sailing. The soul is placed in a central part of the ship, and every magic flame on the boat draws energy from the soul. This way, the flames keep burning for months to come, and they don't go out in harsh weather.
Souls are typically used to guide ships to harbour as well. Sailing at night is common for many ships, as large seas lie between many countries. So having a bright light source to guide you at see is extremely important.
Large community buildings and street lights also use the souls, as light is most commonly needed in every city or town.

Details

Rarety

Moderately rare. It's not the easiest to come across, so markets are littered with souls. But they aren't rare either, as they occur every time a storm passes through the dunes.

Durability

A soul will last you a long time, but depending on what you use it for it will last around: 6 months - 5 years. Some people only buy one soul their entire life, and only uses it to get a constant light source is their homes.

Price

It sells for a high price, but most buyers don't complain as they know souls are hard to find and aren't abundant in the sands.

Appearence

Depending on what type of sand got hit, the souls will have different colours and textures - all within the colour range of sand A sand sculpture with shiny and rough parts, always with a unique shape, it branches out like branches on a tree.