I present you here something I've considered very weird and interesting since several years ago, the coagulation or solidification of common mercury. I've heard of it in Petri Murien books.
It's mostly a curiosity in fact, but it can be useful in confectionning magickal items (that's mostly, for now, the use I can atribute to such a thing), and traditionnaly in Ayurveda it is also what is done, doing with them Shiva Lingam, amulets ...
The good thing is that it can be molded and then doing of it shapes.
Several methods are possibibly used, some more or less quick, some longuer (but with less work). I've heard of an oil able to fix it quiclky, but maybe this oil requires more time to be made.
It is actually a transmutation of mercury into another metal. It's brittle and heavy, not fragile. It let a small colour out of it on the tube glass where it resided during the process.
Here are few images.
Here it's a very small tentative. I've done it twice. The first time I broke the "regulus" I had, and used a part of the powder to re amalgamate with new mercury. In order to see if there were any change in it. None happened.