Umncwebe

Imincwebe yensogcaki ''(amethyst quartz)''

Ngokwesimoncinci, umncwebe owodwa unamachwe acish'aphelela ngokuhleleka; umncwebegcezi (polycrystalline) wakhiwa imincwebe eminingi esimincinci ebizwa imincwebezana; bese isinqumela esingenasimo (amorphous) esifana nenhlaka asihlelekile neze nangokwesimoncinci.

Umncwebe uyisinqumela esiqukethe amachwe ( imizwayi noma izihonyo) ahlelenjwe ngesifanelo esiwuhlaka olusimoncinci. Imincwebe yakhiwa imitshoko ngenqubo ebizwa ukuncwebeka, ewuhlobo lokuguquka kwesimo. Ngokuvamile umtshoko kuba uketshezi, Kodwa imincwebe iyakheka nangohowo. Ngokwesibonelo, iqhwa liyimincwebe yamanzi ebunjwe kusuka emoyeni oqukethe umhwamuko wamanzi (amanzi ahwamukile). Ukuncwebeka kungenzeka ngokukhazeka (freezing) komtshoko olula. Ngezinye izikhathi umchadamezo nengcindezi kuyadingeka ukuze isiqa sibumbe imincwebe. Idayimani liwumncwebe womcalahle obumbeke ngaphansi komchadamezo nengcindezi. Imincwebe iyatholakala ngokwemvelo noma ingakhandwa. Isifundo senzululwazi semincwebe nokwakheka kwayo sibizwa ngokuthi umchazamincwebe. Umdludlungu wokwakheka komncwebe ubizwa ngokuthi ukuncwebeka noma ukushumanqa.