Lapis Aeger or "The stone sickness" is a condition in which people, who have excessively used signum, turn into Rank F to D Saxum themselves. This condition is not race bound and can affect Anima, Vitra and humans.
imagine pushing your body to the limit and then you push further. Muscles and bones could break. It is similar with lapis Aeger. Everything begins to crumble under the strain.
The cause of lapis Aeger is the repeated use of signum over the bodies capability. It is not certain fate that signum user will suffer from lapis Aeger, but repeated use and especially the use beyond someone's capability of signum can accelerate it.
Many people don't notice the first signs of lapis Aeger which is dry skin. If ignored, the dryness will spread over the whole body and patients will notice a soft sparkle from their skin, this is Saxum that slowly wanders to the surface of the body. After this stage it is hard to contain the condition, it will spread, harden and finally suffocate the patient.
In the first stage the condition can be contained by not using signum at all, this however is hard for many people, especially teachers and trainers. Treatment with different Saxum based remedies are applied to the dry skin until it has completely vanished. If the condition is already at a later stage, treatment is difficult, said remedies can still stall the conditions progress but can't heal it anymore. The only way to fully heal advanced lapis Aeger is to amputate the affected parts of the body.
A regulated use of signum is generally the best approach to prevent lapis Aeger, this means: once a person feels slow, tired or generally exhausted by using signum, they should stop and refrain from using signum for at least 8 hours.