Well color temperature is mostly some kind of abstraction dealing with blue-to yellow color balance. It has a physical meaning for incandescent sources as a temperature of a hot black body having the same radiation spectrum. For non-white light, CCT quickly loses its original meaning but there is an agreement within the people working with light to ignore pink-green balance and interpolate resulting yellow-blue color balance of a light as being emitted by a thermal (incandescent) source too. They say "Isotherms perpendicular to Planckian locus" Weird, yeah?
That said, mercury lamp CCT is from about 5500K (bare mercury arc, weak cheap phosphors) to about 4500K (regular MBF) to ~3700K (deluxe) to ~3200K super deluxe, golden lacquer filtered.
