Is luminous mind unconditioned and not impermanent? In AN1.51-52, we find a description of the luminous mind. The Pali version can be found here.

The description in 51-52 implies that it is pre-existing. It's just that the ordinary worldling doesn't discern that it's actually present. But the noble disciples discern that it's actually present.

"yathābhūtaṃ" means "in truth; in reality; in its real essence."

"pajānāti" means "knows clearly".

We know that Nibbana is not conditioned (sankhara) and not impermanent (anicca).

But from the description, it sounds like the luminous mind, which is pre-existing in both worldlings and noble disciples, is always there, just that it is obscured by incoming defilements (kilesa).

Does this mean that the luminous mind is also not conditioned (sankhara) and not impermanent (anicca)?


  “Pabhassa­ra­midaṃ, bhikkhave, cittaṃ. Tañca kho āgantukehi
  upakkilesehi upakkiliṭṭhaṃ. Taṃ assutavā puthujjano yathābhūtaṃ
  nappajānāti. Tasmā ‘assutavato puthujjanassa cittabhāvanā natthī’ti
  vadāmī”ti.
  
  “Pabhassa­ra­midaṃ, bhikkhave, cittaṃ. Tañca kho āgantukehi
  upakkilesehi vippamuttaṃ. Taṃ sutavā ariyasāvako yathābhūtaṃ pajānāti.
  Tasmā ‘sutavato ariyasāvakassa cittabhāvanā atthī’ti vadāmī”ti.
  
  “Luminous, monks, is the mind. And it is defiled by incoming
  defilements. The uninstructed run-of-the-mill person doesn’t discern
  that as it actually is present, which is why I tell you that—for the
  uninstructed run-of-the-mill person—there is no development of the
  mind.”
  
  “Luminous, monks, is the mind. And it is freed from incoming
  defilements. The well-instructed disciple of the noble ones discerns
  that as it actually is present, which is why I tell you that—for the
  well-instructed disciple of the noble ones—there is development of the
  mind.”
Actually, no. Because pabhassa­ra­-citta must arise. Because if pabhassa­ra­-citta will never arise, it can't be defiled by incoming defilements which will arise to defile it, too.

Citta, viññāṇa, mano are the synonym of each other in SN Nidānavagga, assutavasutta:


  “But, bhikkhus, as to that which is called ‘mind(citta)’ and ‘mentality(mano)’ and
  ‘consciousness(viññāṇa)’ —the uninstructed worldling is unable to experience
  revulsion towards it, unable to become dispassionate towards it and be
  liberated from it.


So, pabhassa­ra­-citta is  conditioned (sankhara) and impermanent (anicca) by  SN Khandhavagga, Aniccasutta:


  consciousness is impermanent.


Therefore, paphassara-citta is included in one synonym of citta In abhidhamma, dhammasaṅgiṇī, kusalacittuppādakaṇṭa:


  The citta which is arising while the occation (that 1st wholsome citta
  is arising) means citta, mano, mānasa,    hadaya, paṇḍara (paphassara),   mano,  manāyatana,  manindriya,    viññāṇa, viññāṇa-khandha, and tajjā
  manoviññāṇadhātu — this is the citta which is arising while the occation.
  
  (Translated version is not correct, so I did not quote from that. I have to translate myself.)