 Ida was classified as an S @-@ type asteroid based on the similarity of its reflectance spectra with similar asteroids . S @-@ types may share their composition with stony @-@ iron or ordinary chondrite ( OC ) meteorites . The composition of the interior has not been directly analyzed , but is assumed to be similar to OC material based on observed surface color changes and Ida 's bulk density of 2 @.@ 27 – 3 @.@ 10 g / cm3 . OC meteorites contain varying amounts of the silicates olivine and pyroxene , iron , and feldspar . Olivine and pyroxene were detected on Ida by Galileo . The mineral content appears to be homogeneous throughout its extent . Galileo found minimal variations on the surface , and the asteroid 's spin indicates a consistent density . Assuming that its composition is similar to OC meteorites , which range in density from 3 @.@ 48 to 3 @.@ 64 g / cm3 , Ida would have a porosity of 11 – 42 % . 
