Source	Code	Description	Deposit example
Granitoids	GRA	Coarse-grained plutonic rocks, rich in feldspars and oversaturated in silica (quartz > 20%). Fluxes are mainly recovered from granites (particularly leuco-granites) with minor granodiorites, alkaligranites, and some trondhjemites.	Spruce pine, USA; Montebras, France; Strzeblow, Poland.
Pegmatites	PEG	Very coarse-grained basement rocks, abundant in feldspar, which in most cases are acid diﬀerentiates of granitoids (or syenoids). Fluxes come from all subtypes: plutonic pegmatites, pseudo-pegmatites, meta-pegmatites and pegmatoids.	Sierras pampeanas, Argentina; Black Hills, USA; Kyrkoberget Finland.
Aplites	APL	Diﬀerentiates of granitoid (or syenoid) rocks with a ﬁne-grained texture. Some ﬂuxes are commercialised as “aplites”, as they exhibit an (apparent) aplitic texture, e.g. due to rock alteration.	Botro ai Marmi, Italy; Shigaraki, Japan; Montpelier, USA.
Acid volcanics and subvolcanis	RHY	Extrusive acid rocks (rhyolite, rhyodacite, dacite, comendite) including subvolcanic and hypabyssal types (porphyry). Fluxes are recovered from lavas, domes, pyroclastics (cinerite, tuﬀ, ignimbrite, and perlite) and veins.	Ahuazotepec, Mexico; Lozzolo, Italy; Türkismühle, Germany.
Nepheline syenites and phonolites	NSP	Silica-undersaturated rocks containing feldspars and feldspathoids (nepheline, leucite, etc.). Fluxes are typically obtained as nepheline syenite or its extrusive equivalent nepheline phonolite, but also ultrapotassic rocks can be utilized.	Blue Mountain, Canada; Stjernoy, Norway; Lages, Brazil.
Feldspathics arenites	ARK	Feldspathic sandstones and conglomerates (and the corresponding unlithiﬁed sediments). Fluxes are mostly recovered from arkoses and subarkoses, with some lithic arkoses as well.	Florinas, Italy; Carrascal del Río, Spain; Hirschau, Germany.
Metamorphics	MET	Metamorphic equivalents of previous deposits (e.g. gneiss, porphyroid, micaschist, quartzite) mostly in the greenschist facies. Fluxes are mainly obtained from phyllites and gneisses.	Itapeva, Brazil; Campo Largo, Brazil; Robilante, Italy.
Albitites	ALB	Metasomatic rocks formed through an albitization process that leads to the formation of almost monomineralic bodies (albite after plagioclase and K-feldspar) under the action of metamorphic ﬂuids.	Menderes, Turkey; Ottana, Italy; Salvezines, France.
Epithermal alterations	EPI	Hydrothermal alteration giving rise to peculiar rock types: porcelain stone, eurite, agalmatolite, pinite, toseki and roseki (in Japanese), dunzi or baidunzi (in Chinese) including episyenite and sanidinite.	Amakusa, Japan; Crocetta, Italy; Gusev, Russia.
Alternatives sources		Low-melting minerals alternative to feldspars; end-of-life materials and byproducts, typically feldspar bearing or largely glassy, such as mining residues, waste glasses, and combustion ashes.