The stoney meteorites are further subdivided into several smaller groups. Stoney meteorites called chondrites have millimeter-sized rounded masses called chondrules. The Portales Valley meteorite is an H type chondrite. This means it contains the silicate minerals olivine and bronzite along with some nickel-iron alloy. Achondrites are stoney meteorites that lack these rounded masses.
Iron meteorites consist mainly of an iron-nickel alloy.
Stoney irons have characteristics of both the stoney and iron types. A sample of the Macy meteorite found near Floyd was donated to the Museum by Skip Wilson of Portales. A fragment of the Canyon Diablo meteorite that produced Meteor Crater in northern Arizona was also donated by Skip Wilson. Another iron meteorite was recently verified and prepared for display. A cut surface on this meteorite was polished and etched to reveal the beautiful pattern produced by the intergrowth of the iron-nickel alloys.