far off, 
you point to
	a phosphorescent brick building,
		the windows’ glass iridescent
			in evening light:

my heart of iridium 
	pounds heavy,

		a vacant ringing sound
	five thousand imperfections on film

			fingertips plunging in the dark
		     like nets casting about in dark currents

	[I]quantum in me fuit[/I]

i know what they search for.

I think this is very strong.

I'd omit "slow," because I think it doesn't add much to heavy, or to any kind of rhythmic change. The repetition of "dark" twice in the same stanza seems to detract as well.

The second half is much more vague than the the first, which is focused on the rich imagery. I don't mean that in any kind of negative way. There's still a strong feeling in the second half, but it's worth noting.