Q. [ŋ] vanished between [i], [u] and [n] with compensatory lengthening; [{iu}ŋn] > [V̄øn]

Q. [ŋ] vanished between [i], [u] and [n] with compensatory lengthening; [{iu}ŋn] > [V̄øn]

@@@ update entry to reflect green-ink notes from PE19/97 note #136

In Quenya, the velar nasal [ŋ] vocalized between i, u and n, producing long ī, ū in the process: iñn, uñn > īn, ūn. Tolkien described this sound change in both the Outline of Phonetic Development [OP1] from the 1930s and the Outline of Phonology [OP2] from the 1950s:

But iñn > ín; uñn > ún. Túna, Tukna. [faint] Tuʒna (OP1: PE19/43).
In Quenya dissimilation, by loss of nasality, occurred in ñm, nm > ñgw, nw; and probably in iñn, uñn > ín, ún (via iʒn, uʒn ?) (OP2: PE19/98).

As indicated in both notes, ñ may have passed first through ʒ [ɣ] before vanishing, making this sound change more like the vocalizations of ʒ. This vocalization of ñ before n only occurs after i, u; after other vowels, ñn became nn. However, in the 1950s Tolkien considered a vocalization for ñ before m as well, and this sound change occurred after all vowels (though the vocalizations after i, u occurred first):

ñm, ñn: here (though spelling with ŋ was retained to indicate nasality) ñ ceased to be consonantal and the preceding vowel became nasalized, and lengthened if short: as teŋ-mā > tę̄ma (PE19/82).
ñm, ñn originally remained but iŋ, uŋ early became nasalized ī̜, ų̄ in these positions (the nasality being still retained in Noldorin), later eŋ, aŋ, oŋ became en, an, on by forward assimilation before n, but eŋ, aŋ, oŋ + m became long ę̄, ą̄, ǭ. The spellings ŋm, ŋn were normally retained in PQ (PE19/96-97) @@@ this is a green ink revision, circa 1970.

Somewhat interestingly, Tolkien indicated that ᴹ√TEÑ > ᴹQ. téma in The Etymologies of the 1930s, perhaps an early manifestation of the vocalizations before m. However, téma is the only attested example of these vocalizations before m, and as discussed in the entry on how [nm], [ŋm] became [nw], [ŋgw], the normal phonetic development both before and after OP2 was ñm > ñgw (PE19/43, 47; PE22/149). Thus, the vocalizations before m seem to be a transient idea.

There are a couple examples of the vocalization of ñ before n in The Etymologies of the 1930s, all the result of the nasalization of g in this position:

There is one example that does not fit the pattern of ñ-vocalizations described in OP1 and OP2, however:

Both this example and its deleted precursor seem to show eventual vocalization of gn after the vowels e and a. It may be that in The Etymologies, the vocalization of ñ was universal, or it may be that g > ʒ before nasals instead, and so fell in with vocalizations of ʒ. Without more information it is hard to be sure.

References ✧ PE19/82, 96-98

Order (00200)

Before 02800 [ŋ] assimilated to following [n] after [e], [a], [o]

Related

Phonetic Rule Elements

[iŋn] > [īn] ✧ PE19/98 (iñn > iʒn‽ > ín)
[uŋn] > [ūn] ✧ PE19/98 (uñn > uʒn‽ > ún)
[iŋm] > [īm] ✧ PE19/96 ( > ī̜; before n, m)
[eŋm] > [ēm] ✧ PE19/97 (eŋ + m > ę̄)
[aŋm] > [ām] ✧ PE19/97 (aŋ + m > ą̄)
[oŋm] > [ōm] ✧ PE19/97 (oŋ + m > ǭ)
[uŋm] > [ūm] ✧ PE19/96 ( > ų̄; before n, m)

Phonetic Rule Examples

teŋmā > tēmā eŋm > ēm teŋ-mā > Q. †tę̄ma ✧ PE19/82
teŋma > tēma eŋm > ēm tegma > teñma > tę̄ma > Q. tēma ✧ PE19/97
teŋma > tēma eŋm > ēm ᴹ√TEÑ > ᴹQ. téma ✧ Ety/TEÑ
riŋna > rīna iŋn > īn RIG > Q. -rína ✧ PE17/182

ᴹQ. [ŋ] vanished between [i], [u] and [n] with compensatory lengthening; [{iu}ŋn] > [V̄øn]

References ✧ PE19/43, 47

Related

Phonetic Rule Elements

[iŋn] > [īn]
[uŋn] > [ūn]

Phonetic Rule Examples

l̥iŋnē > l̥īnē iŋn > īn ᴹ✶slignē > ᴹQ. líne ✧ Ety/SLIG
raŋna > rāna iŋn > īn ᴹ√RAG > ᴹQ. rāne ✧ EtyAC/REG
reŋna > rēna iŋn > īn ᴹ√REG > ᴹQ. réna ✧ Ety/REG
riŋna > rīna iŋn > īn riknā > Q. rína ✧ PE19/86
rigna > rīna iŋn > īn ᴹ√RIG > ᴹQ. rína ✧ Ety/RIG
luŋne > lūne uŋn > ūn ᴹ✶lugni > ᴹQ. lúne ✧ Ety/LUG²
tuŋnā > tūnā uŋn > ūn ᴹ✶Tuknā > Tuʒna > ᴹQ. Tūna ✧ PE19/43
θuŋnā > θūnā uŋn > ūn stuknā > Q. thúna ✧ PE19/86