The sap of the Great Pine is highly magical. When refined in @The Ignition Chamber, it becomes a golden fuel source.
Liquid State: Fuel for engines and warmth.
Solid State (Amber): Used to encase spells. Kritz "Boom-Bauble" uses hardened amber to create explosive glass ornaments.
This is the specific magical tradition of the Spire (represented by the @Tinsmith class). It is the fusion of Druidic nature magic (to shape the wood) and Artifice (to shape the metal). A Tinsmith does not just build a robot; they "grow" a @Cog-Kin from living wood and animate it with a soul-gear.