Image: <bdi><a href="https://www.wikidata.org/wiki/Q56247090" class="extiw" title="d:Q56247090"><span title="mineral collector and dealer">Robert M. Lavinsky</span></a></bdi> (CC BY-SA 3.0)
monoclinicuncommonSilicates
Cookeite
(Li,Al)Al4(Si3Al)O10(OH)8
This image displays a pale green, translucent specimen of Cookeite, likely a cut or polished piece, exhibiting a distinct pearly to vitreous luster and a platy or micaceous habit.
Cookeite Physical Properties
Mohs Hardness
2.5Crystal System
monoclinicLuster
pearlyStreak Color
whiteCleavage
perfect on {001}Fracture
unevenSpecific Gravity
2.67Colors
white, pink, pale green, yellowish, colorlessTransparency
transparentType Locality
Barra de Salinas district, Barra de Salinas, Coronel Murta, Jequitinhonha valley, Minas Gerais, Southeast Region, BrazilMineral Group
SilicatesUses
collector, gemstoneAssociated Minerals
tourmaline, quartz, lepidolite, albite, spodumene, berylRarity
uncommonGeological Context
Cookeite is a lithium-bearing chlorite group mineral that typically forms in lithium-rich granitic pegmatites, often as a hydrothermal alteration product of other lithium minerals like spodumene or lepidolite, or in some metamorphic rocks.
