History and Physical Characteristics:
A single 29 g stone was purchased in Erfoud Morocco in August 2007. Some fusion crust remains, although much has been wind ablated away leaving a translucent surface, chemical weathering is minor. Petrography (T. Bunch and J Wittke, NAU):
Monomict cumulate basalt breccia that is highly shocked. Plagioclase is completely recrytallized. Pyroxenes are partially recrystallized, unrecrystallized pyroxenes have reduced birefringence, shock lamellae, and are darkened by shock decorations. Unusual amount of metal for a eucrite (vol. % = 4). Sparse, but large chromite grains (0.3 to 1.1 mm) are present. Weathering grade is low with some staining around metal grains. Mineral compositions:
Fs45.7Wo1.9 (FeO/MnO = 28); lamellae, Fs8.2Wo14.8; augite, Fs16.6Wo46.1. Plagioclase, An 87.8, chromite cr# = 81, and metal Ni = 0.87 wt %.
Name : NWA 4960 Class : Achondrite, Eucrite S5/W-low Region: Erfoud, Maroco Date : 03.2007 TKW : 29g
Highly shocked, but fresh eucrite. Contain alot of iron.