yintoni umthi ogudileyo
Context:Umthi ogqunywe ngamatye, okwaziwa nangokuthi ngumthi ogqunywe ngamatye (ukusuka kwisiGrike samandulo πέτρα elithetha 'ilitye' okanye 'ilitye'; ngokoqobo 'umthi oguquke waba litye'), ligama elinikwa uhlobo olukhethekileyo lomthi ogqunywe ngamatye, intsalela egqunyiweyo yezityalo zasemhlabeni. Ukuguqulwa kwamatye sisiphumo somthi okanye izityalo ezinjengomthi eziye zatshintshwa ngamatye ngenkqubo ye-mineralization edla ngokubandakanya i-permineralization kunye nokutshintshwa. Izinto eziphilayo ezakha iindonga zeeseli ziye zaphindaphindeka ngezimbiwa (ubukhulu becala isilikha ngohlobo lwe-opal, i-chalcedony, okanye i-quartz). Kwezinye iimeko, isakhiwo sokuqala somthi sinokugcinwa ngokuyinxenye. Ngokungafaniyo nezinye izityalo eziye zafunyanwa, ngokuqhelekileyo eziye zavela ngokushicilelwa okanye ngokucinezelwa, iinkuni ezenziwe ngamatye zifana nezinto eziphilayo ezazisetyenziswa ekuqaleni.  Inkqubo yokuqhekeka kwenzeka phantsi komhlaba, xa iinkuni zingcwatyelwa emanzini okanye eluthuthwini lwentaba-mlilo. Ubukho bamanzi bunciphisa ubukho beoksijini ethintela ukubola kwe-aerobic yintsholongwane kunye nefungi. Amanzi anezimbiwa ahamba phakathi kwezinto ezinobungozi angakhokelela kwi-permineralization, eyenzeka xa izimbiwa zikhutshwa kwisisombululo ezizalisa ingaphakathi leeseli kunye nezinye iindawo ezingenanto. Ebudeni bokutshintshwa kwesityalo, iiseli zeso sityalo zisebenza njengetemplate yokwenziwa kwezimbiwa. Kufuneka kubekho ulungelelwaniso phakathi kokubola kwecellulose kunye nelignin kunye ne-mineral templating ukuze iinkcukacha zeeseli zigcinwe ngokunyaniseka. Uninzi lwezinto eziphilayo zihlala zibola, nangona kunjalo ezinye ze-lignin zisenokuhlala. I-silica ngohlobo lwe-opal-A, inokufaka i-encrust kwaye ingene kwiinkuni ngokukhawuleza kwimimandla eshushu eshushu. Noko ke, iinkuni ezenziwe ngamatye ngokuqhelekileyo zidla ngokunxulunyaniswa nemithi eyayingcwatywe kumgxobhozo omncinane weengxondorha neendawo ezikhukulayo okanye kwiinduli zeentaba-mlilo. Ihlathi apho izinto ezinjalo ziye zaba ngamatye liyaziwa njengehlathi elenziwe ngamatye.
Iinkuni ezenziwe ngamatye yenye yeefosili, sisityalo esinendawo yangaphakathi ethatyathelwe indawo lilitye ngokucinezelwa nangokukhutshwa kwizigidi zeminyaka