Locrian mode

The Locrian mode is a musical mode or diatonic scale. It may be considered a minor scale with the second and fifth scale degrees lowered a semi-tone. The Locrian mode may also be considered as a scale beginning on the seventh scale degree of any Ionian, or major scale.

Some examples:
*The B Locrian mode starts on B and contains the same notes as C Major scale. (B, C, D, E, F, G, A, B)
*The E Locrian mode starts on E and contains the same notes as F Major Scale. (E, F, G, A, B♭, C, D, E)

The Locrian mode is the only modern diatonic mode in which the tonic chord is a diminished chord, resulting in a tonic chord that is considered dissonant. For example, the tonic chord of B Locrian is spelled B, D, F. The interval between the tonic (B) and the dominant (F) is a diminished fifth or tritone.

The Locrian mode was of mainly theoretical importance in classical music before the 1850s because of the large amount of dissonance created within the scale and its corresponding chord. In more recent musical pieces, the dissonance or musical imbalance created by the Locrian scale and chord have fallen back in favour (especially in Jazz) in order to create a sense of large tension.

Heavy metal musicians also use Locrian mode; one notable example is the guitar introduction to Metallica's "Enter Sandman". Another example, more from the progressive hard rock genre, is the first section of the instrumental "YYZ" by Rush: the synthesizer melody is in C Locrian, over a guitar riff based on the C-Gb tritone. "Stash" by Phish gets its dissonant, irregular sound from the D Locrian mode.

The Locrian mode comes from the music theory of ancient Greece. However, what is now called the Locrian mode was what the Greeks called the Mixolydian mode. The original Greek Locrian mode seems to have been tuned to a natural A mode, but how it differed from the Aeolian and Hypodorian modes is unclear.