Red Phazite

From Wikitroid, the Metroid wiki

Red Phazite is a rare form of Phazite. It may or may not have a connection with the Orange Phazon found in the Impact Crater. It can not be pierced by using the Nova Beam in combination with the X-Ray Visor. Pirate Commanders wear Red Phazite armor. They are the only type of Space Pirates that are allowed to do so, because it is valuable to them. It is interesting to note that Omega Ridley either cannot generate this type of Phazite or in his supreme arrogance generated normal Phazite to toy with Samus thinking that he was powerful enough to defeat her regardless. Either way, this flaw proved to be his downfall. It may also be possible that either Red Phazite is completely unable to generate or a large enough quantity could not be spared to give Omega Ridley that ability, seeing as Commanders are not exactly the most abundant enemy as only one is seen in-game.