Her music features canonic structures and prominent, sometimes exclusive, glissandos, being "characterized by extremely strict, even rigid technical procedures (canonic structures), which are often worked out with unusual musical materials (glissandi)". Her music is postminimalist, marked by the tension "not only between material and technique (...an attempt to give structure to chaos), but even more so between what would have to be termed 'sober-technical' compositional principles and the genuine direct expressive power and emotionality of the music".
As one interview describes:
For Gloria Coates, artistic expression is a spiritual necessity. She has great interest and significant participation in painting, architecture, theater, poetry, and singing—but it is through composing that she taps into a wellspring of abstracted emotionality that the others cannot reach. Whatever the veiled expressions of her work may be, there is an undoubted emotional richness present, which if not concretely knowable is at least viscerally felt by the audience. Canons constructed of quartertones and glissandos evoke gloomy instability, but also unearthly beauty.
Mark Swed: “Coates is a master of microtones, of taking a listener to aural places you never knew could exist and finding the mystical spaces between tones.” [5]
As is described by Kyle Gann' liner notes to one of her albums:
Behind the variety of such techniques, behind even the varying deployment of similar structures, one hears Coates's constant aesthetic: her sense of each movement as a unified gesture, her almost post-minimalist unidirectionality. Above all, while sadness, anger and mysticism appear in her work with stylized clarity, they are subsumed to an overarching tranquility that often has the last word, and always the most important one.
In Kyle Gann's article "A Symphonist Stakes Her Claim", Gloria Coates was crowned, "the greatest woman symphonist", for her passionate pursuit and persistence in a domain that is dominated by men. However, this ambitious pursuit to be a woman symphonist has not been a conscious effort to set herself apart from the other female composers, instead in an interview she commented that it came through a natural manifestation trying to convey something deep within her. "When I did, I thought, 'That's really gutsy of me to call it a symphony,'" she said from her home in Munich, "I always had an idea of symphonies being in the 19th century, somehow. I never set out to write a symphony as such. It has to do with the intensity of what I'm trying to say and the fact that it took 48 different instrumental lines to say it, and that the structures I was using had evolved over many years. I couldn't call it a little name."
Painting
Besides composing, Gloria Coates also paints abstract expressionistic paintings that are often used as the covers for her albums. In her paintings, complementary colours such as red and green, yellow and blue, interact and mix with one another in the small strokes. The painterly manner, with layers of swirls of colours, is reminiscent of the style of Vincent van Gogh.
Compositions
The following is a list of Coates' musical compositions based on Theresa Kalin, edited by Christian Dieck
a) Works for orchestra
Symphony No. 1 „Music on Open Strings“ (1972)
Symphony No. 2 „ Music on Abstract Lines/ Illuminatio in Tenebris“ (1973/74)
Symphony No. 3 „ Symphony for Strings“/ „Symphony Nocturne“ (1974)
Symphony No. 3 – 2. version (Concerto for violin) (2006)
Symphony No. 4 „Chiaroscuro“ (1984/89)
Symphony No. 5 „Drei mystische Gesänge“ (text: Alexandra Coates) for choir and orchestra (1985)
Symphony No. 6 „Music in Microtones“ (1985/86)
Symphony No. 7 (1989/90)
Symphony No. 8 „Indian Sounds“ for voices and orchestra (1990/91)
Symphony No. 9 „Homage to Van Gogh“ (1992-1994)
Symphony No. 10 „Drones of Druids on Celtic Ruins“ for brass and percussion (1992/93)
Symphony No. 11 (1997)
Symphony No. 12 (1998)
Symphony No. 13 (2000)
Symphony No. 14 (2001–02) "The Americans"
Symphony No. 15 (2004/05) "Homage to Mozart"
Symphony No. 16 „Time Frozen“ (1993)
Vita –Anima della Terra (text: Leonardo da Vinci) for soli, mixed choir and orchestra (1972/76)
Planets (1973/74)
Fonte di Rimini (text: Leonardo da Vinci) for mixed choir and orchestra (1976/84)
Transitions (1984)
Cantata da Requiem (1972)
b) Chamber orchestra with voice
Voices of Women in Wartime. Cantata da da Requiem for soprano solo, viola, violoncello, piano and percussion (1972)
The Force for Peace in War. Cantata da Requiem for soprano, tape and orchestra (1988)
Wir tönen allein (Paul Celan) for soprano,timpani, percussion and string orchestra (1988)
Rainbow across the Night Sky for female voices and ensemble (1990)
Emily Dickinson Lieder for solo voice and Chamber orchestra (1989)
Cette Blanche Agonie (text: Stéphane Mallarmé) for soprano, English horn, oboe, timpani, percussion and string orchestra (1988)
String Quartet No. 10 „Among the Asteroids“ (1971/76)
Halley´s Comet Nonet for flute (piccolo), oboe (English horn), bassoon (contrabassoon), horn and string quintet (1974)
a) Works for choir
Dies Sanctificatus from Saint Joan for soprano, alto, tenora cappella (1961)
Missa Brevis (1964)
Sing onto the Lord a new song for mixed choir a cappella (1964)
Te Deum aus Saint Joan for mixed choir a cappella (1964)
The Beautitudes for soli and organ (1978)
Der Schwan from Licht (Alexandra Coates) for mixed choir a cappella (1988)
b) Works for Solo voice
1. Voice with piano
The Sighing Wind (Gloria Coates) (1950)
Twilight (Gloria Coates) (1961)
Ophelia Lieder from Hamlet by Shakespeare for middle voice and Liederharfe (1964/65)
Komplementär (Friederike Mayröcker) (1999)
Catch the wind (text: Alexandra Coates)
Songs on poems by Emily Dickinson for voice and piano
2. Solo voice with ensemble
Voices of Women in Wartime- Cantata da Requiem for sopran solo, viola, violoncello, piano and percussion (1972)
The Tune without the Words (Emily Dickinson) for voice, Glockenspiel, percussion and timpani (1975)
Go the Great Way (Emily Dickinson) for voice, percussion, timpani and organ (1982)
C. Electronic Music
Eine Stimme ruft elektronische Klänge auf for Live electronics, modulator, voice and laser (1971)
Neptune Odyssey for tape. Musique concrete (1975)
Ecology No. 1. Realized in the electroacoustic Studio of the Musikakademie Krakau (1978)
D. Multimedia
Music heard visually Presto (1972)
Cosmos Klang (1973)
Musik-Kunst (1990) Premiere of the Symphony No. 4, performance of Symphony No. 2, Stage work with paintings from Ursula and Dietmar Thiele-Zoll
Abraham Lincoln´s Cooper Union Adresson poems by Gloria Coates and texts by Martin Luther King (2003)
Entering the Unknown for spinett, string quartet and video (Birgit Ramsauer) (2004)
E. Theatre
Bühnenmusik zu Jedermann for flute, oboe and percussion (1961)
Musik zum Schauspiel Hamlet von Shakespeare for choir, organ and chamber orchestra (1964/65)
The three Billy Goat´s Gruff Interactive music theatre piece for children between 3–6 years (1965)
La Vox Humaine (von John Cocteau) for two percussionists and ballet (2010)
Stolen Identity. Chamber Opera for soprano, countertenor, Bassbariton, string quartet, piano and percussion (2012)
F. Music in film productions
Politik nach Notenblatt (1981, Klaus Croissant, BR-Fernsehen-Dokumentation) with Voices of Women in Wartime
Turin- Die geräderte Stadt (1983, Gabriel Heim, BR-Fernsehen-Fernsehfilm) with Stein quartet No. 4
Death of Cain (2001, Ido Angel, Ido Angel Films Tel Aviv, Israel- Independent Film) with Symphony No. 2
Another Kind (2011, Jonathan Blitstein, Blitstein Films- Independent Film) with some orchestral pieces
Articles by Gloria Coates (selection)
Lutoslawski im Seminar. In: Neue Musikzeitung, October/ November 1975, No. 5, 24. year., p. 12
Desert Plants. A History of American Music. Rundfunkproduktion WDR 1978 (Ms.)
Zusammen mit Detlef GOJOWY: Rezension zu Walter Zimmermanns Dessert Plants. In: Die Musikforschung, 33, 1980, booklet 2, p. 206-207
Erstes Internationales Musikfestival in der UdSSR. In: Musica, 25. Jahrgang 1981, booklet 4, p. 365-366
Russian immigrant composers in the United States. Rundfunkproduktion WDR 1986 (Ms.)
A Cockatoo Will Do. In: The Twentieth-Century Recorder (USA), XXXI, Dez. 1990, No. 4, p. 17-19
Karl Amadeus Hartmann/ Reflektiert und in die Zukunft gedacht. In: Musica Viva; Eine Sprache der Gegenwart 1945-95, edited by Renate Ulm for the Bayerischer Rundfunk 1995, Mainz 1995, p. 277-283, also: p. 7, 236-245
15 programs in: Open House West Germany Radio, Cologne
Music little reviews for the: State Times, Baton Rouge, Louisiana
Symphonies
Symphony No.1 (1973)"Music on Open Strings" 1980 (live) Musica Viva Munich, Bavarian Radio Symphony Orchestra, Elgar Howarth, cond. (cpo 999 392-2
Gloria Coates: Symphony No. 15 (2004–2005), Cantata da Requiem (1972), Transitions (1984) (Naxos 8.559371); Vienna Radio Symphony Orchestra/Boder, Teri Dunn (Sopran)/ Talisker Players, Ars Nova Ensemble Nuremberg/Heider (2007)
Gloria Coates: At Midnight (Tzadik New York, 2013)