>>130823
You could potentially use an amalgam of Iron Oxide and Mercury to fake it.
The challenge is getting amalgamation to occur without decomposing. You'll need another ingredient or process to make that happen, which is the million dollar, or €70k question.
protip: The magnetic moment per iron atom increases at 275 K, allowing the iron to form a metastable alloy with mercury, which decomposes at about 360 K.
If you wanted something that would pass for 'real' (or perhaps is the real red mercury) then Hg2Sb2O7, DuPont produced this under CAS: 20720-76-7 is a red-brown color. You can buy a copy of the patent #2036149 for this from SoyuzPatent. Promecologia in Ekaterinburg was the only state licensed producer, but they are long bankrupt.
Also: All of this is extremely, extremely toxic.