A Geoscience Digital Image Library

TitleOlivine in basalt, Arizona
DescriptionMany basalts contain olivine, and sometimes the crystals are large and in clumps as shown here. Olivine is not a recognized mineral name; it is instead a general term given to a series of compositions between two end members, fayalite (Fe2SiO4) and forsterite (Mg2SiO4). Fayalite-rich olivines have a higher index of refraction, are denser, and have a darker color than forsterite-rich olivines. Virtually all specimens contain iron and magnesium. Telling compositon from appearance is inexact, so the general name olivine is used. This specimen is 13 cm across.
LocationUSA ▹ Arizona ▹ Gila. San Carlos Indian Reservation.
PhotographerNessa Eull. 2001-05-22.
CollectionDexter Perkins Mineral Collection.
Key wordsOlivine, Arizona
Tech details561 KB. Hand specimen. Fujifilm FinePix S1Pro digital camera; 60 mm AF Nikon micro lens.
GeoDIL number528