Is it normal that my Mac nearly overheats from downloading this Blockchain?
The fan is meanwhile blowing full speed and still I can nearly bake an egg on the alu housing...
It will get quite warm verifying all the blocks, yes.
Which Mac are you running, out of curiosity?
MacBook Pro (Retina, 15-inch, Early 2013)
2.4 Ghz
8 GB 1600 MHz DDR3
Model Identifier: MacBookPro10,1
Processor Name: Intel Core i7
Processor Speed: 2,4 GHz
Number of Processors: 1
Total Number of Cores: 4
L2 Cache (per Core): 256 KB
L3 Cache: 6 MB