Edit - It could be a driver /final output (triode) tube for an older Harris or RCA UHF TV transmitter.
http://www2.l-3com.com/edd/pdfs/broadcast_IOTD 130D.pdf
Either that, or:
Looks like a coaxitron tube - used in high power radars - think FAA ground radars, AWACS and E-2C AEW radars and the like. The beefy lugs with the holes are likely filament connections - most have low voltage, high current filaments. 1 Megawatt power peak, but something like 400 Watts average - the peak power is pulsed power, there for a microsecond or less.
Yes, lots of BeO to deal with, so keep it whole. What part is gold? I've seen many coaxitrons, but I've never seen one with gold anywhere. Most are copper, beryllium, and plated (Ag) copper, with some having a tungsten slug for heat sinking, and maybe some copper mesh at the sampling port. We used to have to bust up smaller ones on the ship - dunk it in a 5-gallon bucket of water, strike it, and the bottom of the tube would come loose - and functioned as an ashtray...... :mrgreen: Then we'd dump the water over the side with the BeO contained...
Definitely a collector item - there are lots of old tube collectors. Ebay, Antique Radio Forums, and Antique radio classifieds are just some listing options.