Nope Its definitely burned out. I'd buy a replacement one 

Nice, thanks

Naaahh it's fine, just a tiny bit of blackening. I'd rather say that it still works 100%.

But! It does work. Not very bright any more, but the color is right and so is CRI! Just a bit warmer!

❓¿?❔⍰❓❓❓  ... my brain stopped braining. HOW IN THE WORLD IS THIS THING STILL WORKING! Hasn't it blown up

But... You see)

Anyway, what happened with a clear lamp? Das ist kaputt. No doubts) It was already heavy used and died in my luminaire over night. Arc tube corroded through and some of its contents leaked to outer bulb. So there is no more vacuum and you see that pretty blue glow discharge that shunts ignition pulses and does not allow the lamp to ignite any more. Pretty, right? It is that glow discharge that causes heavy black sputtering on the outer bulb, to answer you question. Note that the discharge around the getter has somewhat reddish coloration. Almost certain it sputters some metal from it causing a red glow. But how in the world the first lamp still ignites?? That's some miracle. When heavy sputtering occurs, it captures a lot of gas from the volume, a way that neon lamps usually die. Probably enough gas get cleared ro restore vacuum in the outer volume to allow the lamp to ignite again. But... What about the leak from the burner. How it managed to get stopped? I do not know. May be it leaked not through the corroded wall, but along the lead-in, and frit filling seal that plugs the lead-in tube somewhat managed to restore its tightness? This lamp somehow returned from the dead

Well that's interesting!

And what do you think about this one?

I just noticed that hit was a PHILIPS MASTER  lamp these things do a great job! I've got two of these that I use in summer to light the garden when guests come over with a DIY compact fixture with an external ballast that I had made, one lamp is a spare. I got them from Italy with some other lamps because they are pretty expensive here in Greece.

Yep, Philips did it right just from the first series of their ceramic MH about 30 years ago from now. Especially in /942 color. Stock up with these lamps if you like them, now is a good time.
 

Am I already qualified for pathological hoarding, or that is not enough

These come from much neglected set of luminaires. I picked 15 downlighter cans with these (and also some nice Swiss Tridonics) but out of 15 lamps only 3 were still alive.

Date codes 1F, 1J, 1K, still radioactive series.

Note that no EOL lamps exploded, these all fail peacefully, including the one that leaked in my hands!

I found two MV bulbs, both have black arctubes No signs of life with a tesla coil.

Yep, Philips did it right just from the first series of their ceramic MH about 30 years ago from now. Especially in /942 color. Stock up with these lamps if you like them, now is a good time.
 

Yes these lamps are great! ("Stock up with these lamps if you like them, now is a good time.") Unfortunately yes because I'm afraid that these lamps and any other (except LED junk) will soon be history.
 

Am I already qualified for pathological hoarding, or that is not enough

These come from much neglected set of luminaires. I picked 15 downlighter cans with these (and also some nice Swiss Tridonics) but out of 15 lamps only 3 were still alive.

Date codes 1F, 1J, 1K, still radioactive series.

Note that no EOL lamps exploded, these all fail peacefully, including the one that leaked in my hands!

Well these are a lot of burnt ones!  You just turned your table in to graveyard for PHILIPS master lamps  

I found two MV bulbs, both have black arctubes No signs of life with a tesla coil.

Have you tested them with MV gear?

I have seen various EOL HPS lamps with completely blackened arc tubes, as well as heavily used metal halide and mercury vapor lamps.

Now I have this lamp to. The arc tube is black  but it still works just fine.