ˈpenəˌnīt noun
also pen·nine ˈpenə̇n, -ˌnīn
( -s )
Etymology: penninite from German pennin (from Pennine Alps) + English -ite; pennine from German pennin
: a mineral approximately (Mg,Fe,Al) 6 (Si,Al) 4 O 11 (OH) 8 of the chlorite group consisting of a basic aluminosilicate of magnesium, iron, and aluminum, that is monoclinic and is commonly emerald or olive green (hardness 2.-2.5, specific gravity 2.6-2.85)