Malachite is a massive fusion, nearly equal in size to Sugilite on all fours and Alexandrite on her back legs. She possesses six arms, of which the lower four function as legs. She has four eyes with light green irises and pointed teeth. Her first set of eyes function as eyebrows. Her eyes change shape based upon who is controlling her, with her eyes being small and catlike as Jasper and a larger, rounder shape as Lapis. Her wavy pale-green hair, styled in a star like Alexandrite's, is a short bob like Lapis', but wild and frizzy like Jasper's. Her skin is seafoam green with dark green stripes, and its pattern is similar to Jasper's. She has two torsos joined, similar to a Centaur. Her upper torso and arms are longer and more slender while her lower torso and four limbs are more muscular. The upper half of her outfit, which is a deep-green and greenish-black stretched halter top, has a pattern like Lapis' suit with a neckline like Jasper's while its lower half is a greenish-black "uniform" similar to Jasper's with a V-neck "collar" that connects to form a Yellow Diamond insignia, serving as a waistband for her upper torso.
Due to being a fusion, Malachite's personality is a twisted combination of both Jasper and Lapis' character traits. However, because of her being a very unstable fusion held together with anger, their personalities are present rather than merging into a new one (much like how Alexandrite displayed the individual personalities of Amethyst, Garnet, and Pearl rather than merging into one). Once formed, she was shown as having Jasper's disdain for the Crystal Gems and wishing to see them destroyed, but Lapis' consciousness was later shown to be the most dominant, as she was able to overpower Jasper's.
In "Chille Tid", Lapis is shown to be struggling to maintain her dominance over Jasper, it is also clear that if Lapis is distracted for the shortest period of time, Jasper can gain control. At the end of the episode, Malachite's personality starts to dominate and suppress Lapis' own, much in the same way Pearl was afraid it would happen to Amethyst and Garnet when fused into Sugilite for too long. It ends on a chilling note with Lapis refusing the name Lapis and proclaiming that they are Malachite now, indicating that Malachite's own true personality is formed and is taking over. It is unknown if Jasper has also lost herself to the fusion.
In "Super Watermelon Island", Lapis completely loses control of Malachite and Jasper takes over, and a battle against Alexandrite ensues. Over the course of the battle, it seems like Jasper and Lapis' voices occasionally become more in sync; whether this is true or even intentional is unknown, but it could signify that Malachite was finally gaining her own identity.
Malachite possesses standard Gem abilities, bubbling, shapeshifting, fusion, regeneration, agelessness, and superhuman strength/durability.
When fused with Ruby, Sapphire, Pearl, Amethyst, Peridot, Rose Quartz, Ice, Marshallsussmanite, and Emerald, they form Cadmoindite.
Crash Helmet Proficiency: Being a fusion of Jasper, Malachite can summon her weapon: a tangerine, crystalline helmet. The helmet acts both as a weapon and armor; a hammer-like protrusion in the front of the helmet allows her to use it to charge, slam, and headbutt her opponent while a clear orange-tinted visor extends down, covering the upper part of her face. The sturdiness of the helmet rivals that of Garnet's gauntlets, as Jasper is shown continuously countering her attacks.
Hydrokinesis: Malachite inherits Lapis' power to manipulate water and liquid material. She has demonstrated she can form water into various constructs that she can control. She is shown to form hands out of water that she can use to smite enemies. She is also able to form chains to entangle or trap enemies with. She can control water even when not attached to a larger body, causing it to levitate.
Matter State Manipulation: Malachite can change the state of matter of water using her hydrokinetic abilities, causing it to turn into ice. She uses the ice for both offense and defense, as projectiles or a shield.
Flight: Malachite can use Lapis Lazuli's water-wings to propel herself at high velocities as an evasive maneuver or as a method of transportation.
Spin Dash: Malachite can roll herself into a ball-like shape and propel herself at foes at great speeds. She has inherited this ability from Jasper.
Comet Charge: While airborne, Malachite can lunge at enemies with alarming speed and power. This attack is very powerful as shown when it knocks Alexandrite to the ground.
Malachite is the tallest double fusion of GemCrust. She tall 8m02
When asked who would win, Kutnohorite or Malachite, GemCrust answered that Kutnohorite would, but if they fought near water, the winner would be Malachite.