Unfortunately, I currently cannot find information about the substance H2Cr5O12. Based on its formula structure, it seems to be a compound of hydrogen, chromium, and oxygen, but there is no specific information about it in the chemical databases I have access to. It could be a minor, complex, or yet to be discovered or named compound according to international chemical standards.
I will try to search more and update the information if found. In this particular case, I advise you to consider discussing with chemical experts or referring to further formal chemical information sources.