"Argillite" may also refer to Argillite, Kentucky.
Sedimentary rock
A piece of black argillite from Haida Gwaii, Canada
indurated clay particles
Grey chunks of graptolitic argillite on Pakri Peninsula, Estonia; yellowish and white chunks are limestone

Argillite ( t/) is a fine-grained sedimentary rock composed predominantly of indurated clay particles. Argillaceous rocks are basically lithified muds and oozes. They contain variable amounts of silt-sized particles. The argillites grade into shale when the fissile layering typical of shale is developed. Another name for poorly lithified argillites is mudstone. These rocks, although variable in composition, are typically high in aluminium and silica with variable alkali and alkaline earth cations. The term pelitic or pelite is often applied to these sediments and rocks. Metamorphism of argillites produces slate, phyllite, and pelitic schist.

Belt Supergroup

The Belt Supergroup, an assemblage of rocks of late Precambrian (Mesoproterozoic) age, includes thick sequences of argillite, as well as other metamorphosed or semi-metamorphosed mudstones.[1] It is exposed primarily in western Montana, including the Bitterroot Valley and Bitterroot Mountains, the Missoula area, Flathead Lake, and Glacier National Park, and in northern Idaho. There are also minor occurrences in northwestern Washington and western Wyoming.[2] Excellent outcrops of deep purple, wine red, red, blue, turquoise, and green argillites of the Belt Supergroup can be seen in Glacier National Park in northwestern Montana and in Wolf Creek Canyon along US Interstate 15 in west-central Montana.[3]

Other Languages
العربية: أرجيليت
aragonés: Archilita
azərbaycanca: Argillit
башҡортса: Аргиллит
български: Аргилит
eesti: Argilliit
español: Argilita
Esperanto: Argilito
euskara: Argilita
فارسی: آرژیلیت
français: Argilite
հայերեն: Արգիլիթ
italiano: Argillite
ქართული: არგილითი
қазақша: Аргиллит
Кыргызча: Аргиллит
lietuvių: Argilitas
magyar: Agyagpala
Nederlands: Argilliet
oʻzbekcha/ўзбекча: Argillitlar
polski: Argilit
português: Argilito
русский: Аргиллит
српски / srpski: Аргилит
srpskohrvatski / српскохрватски: Argilit
українська: Аргіліт
Tiếng Việt: Sét kết