Siltstone
It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility.Silt is defined as grains 2–62 μm in diameter, or 4 to 8 on the Krumbein phi (φ) scale.[9][10] Unless the siltstone is fairly shaly, stratification is likely to be obscure and it tends to weather at oblique angles unrelated to bedding.[17] Highly energetic processes are required to break these grains down to silt size.[23] Siltstones form in relatively quiet depositional environments where fine particles can settle out of the transporting medium (air or water) and accumulate on the surface.
Sedimentary rockclastic sedimentary rockmudrockclay mineralfissilitytight gasunconventional reservoirnatural gashydraulic fracturingancient Egyptcosmetic palettesWadi Hammamatclasticsandstonesconcretionsstratificationweatherquartzdepositional environmentsturbiditeCheltenham BadlandsChek ChauCanadian Journal of MicrobiologyBibcodeIgneous rockAdakiteAndesiteAlkali feldspar graniteAnorthositeApliteBasaltAlkali basaltPicrite basaltBasaltic trachyandesiteMugeariteShoshoniteBasaniteBlairmoriteBoniniteCarbonatiteCharnockiteEnderbiteDaciteDiabaseDioriteNapoleoniteDuniteEssexiteFoidoliteGabbroGraniteGranodioriteGranophyreHarzburgiteHornblenditeHyaloclastiteIcelanditeIgnimbriteIjoliteKimberliteKomatiiteLamproiteLamprophyreLatiteLherzoliteMonzograniteMonzoniteNepheline syeniteNepheliniteNoriteObsidianPegmatitePeridotitePhonolitePhonotephritePorphyryPumicePyroxeniteQuartz dioriteQuartz monzoniteQuartzoliteRhyodaciteRhyoliteComenditePantelleriteScoriaShonkiniteSoviteSyeniteTachylyteTephriphonoliteTephriteTonaliteTrachyandesiteBenmoreiteTrachybasaltHawaiiteTrachyteTroctoliteTrondhjemiteWebsteriteWehrliteArgilliteArkoseBanded iron formationBrecciaCalcareniteClaystoneConglomerateCoquinaDiamictiteDiatomiteDolomiteEvaporiteGeyseriteGreywackeGritstoneItacolumiteJaspilliteLateriteLigniteLimestoneLumachelleMudstoneOil shaleOolite