Grade 6 Dark Matter

Grade 6 Dark Matter is a catalyst.

Source
Grade 6 Dark Matter can be can be obtained from exploratory voyages or purchased from vendors.

Exploratory voyages
Grade 6 Dark Matter can be obtained from a company submersible exploratory voyage to the following areas:
 * The Upwell, Deep-sea Site

Vendors
Grade 6 Dark Matter can be purchased for from the following vendors:
 * Unsynrael - Limsa Lominsa Lower Decks
 * Apartment Merchant - Topmast Apartment Lobby, Lily Hills Apartment Lobby, Sultana's Breath Apartment Lobby, Kobai Goten Apartment Lobby
 * Alaric - Old Gridania
 * Haneko Burneko - The Waking Sands
 * Nanabe - Ul'dah - Steps of Thal
 * Frine - The Pillars
 * Junkmonger - Idyllshire
 * Independent Merchant - Rhalgr's Reach, The Lochs, The Peaks, The Ruby Sea, Yanxia
 * Blessed Merchant - The Fringes
 * Merchant & Mender - The Fringes, The Peaks, The Ruby Sea, Yanxia
 * Tribe Merchant - The Fringes
 * Local Merchant - The Lochs
 * Dotharli Merchant & Mender - The Azim Steppe
 * Mol Merchant & Mender - The Azim Steppe
 * Oroniri Merchant - The Azim Steppe
 * Traveling Merchant - The Azim Steppe
 * Enclave Merchant - The Ruby Sea
 * Hingan Merchant & Mender - The Ruby Sea
 * Village Merchant & Mender - The Ruby Sea
 * Village Merchant - Yanxia
 * Tokohana - Kugane

It can also be purchased for 100 from the following vendors:
 * Storm Sergeant - Wolves' Den Pier

It can also be purchased for 345 company seals from the following vendors:

Uses
Grade 6 Dark Matter is used in crafting the following items:
 * - Alchemist, Armorer, Blacksmith, Carpenter, Culinarian, Goldsmith, Leatherworker, Weaver.