I have this heavy jade piece. I also see there is a tiny hole in the "egg" which leads me to think this may be a veneer of jade. Both pieces together are nearly a pound. The egg is 2" X 1-3/8" and the "nest" is 3-1/4" X 2-3/4". This has that ice cold feel of jade and is a veneer enough to produce that coldness. It looks black into the egg thru that small hole..the same black as is on the bottom of the "nest".
Malachite is often mistaken for jade but easily recognizable by its wood-like or water-like patterns.
It is a copper mineral in a beautiful shade of green and you can admire a whole hall in the imperial palace in St. Petersburg, a priceless room made of gold and malachite (in sizes so big that it is unbelievable!).
Like this man-sized urn: