Tectosilicates Flashcards
SiO2 that hexagonal prisms
terminated by a combination of positive and
negative rhombohedrons
Quartz
SiO2 that has smooth, waxy, or glassy appearance
Chalcedony
SiO2 that has tetragonal crystal structure different from quartz and tridymite
Cristobalite
SiO2 that has a triclinic crystal system
Tridymite
Opal is a
Mineraloid
SiO2 nH2O
Opal
KAI Si3O8
Potassium feldspar
Crystal system of potassium feldpar
Monoclinic
Restricted to quartz-free
rocks
Feldspathoid group
(Na, K) AlSiO4
Nepheline
Crystla system of nepheline
Hexagonal
KAl Si2O6
Leucite
Commercial source of alum
Leucite
Na6 Ca2 Al6 Si6 O24 (CO3)2
Cancrinite
Na4 (AlSiO4)3 Cl
Sodalite
mineral changes color in direct
sunlight and turns back into its original
color in the dar
Tenebrescence
(Ca, Na) (Al,Si) Al Si2 O8
Plagioclase fledspar
Crystal system of plagioclase feldspar
Triclinic
effect that causes a mineral to display dark,
metallic-like color shimmers, usually in blue
and green colors
Labradoresence
optical effect when a mineral displays a
milky, bluish luster across a mineral’s surface
Adularescene
NaAl Si3O18
Albite