| Newsletter |
33,2 |
| Location |
Miller Range |
| Field Number |
17871 |
| Dimensions (cm) |
1.7 x 1.8 x 1.2 |
| Weight (g) |
7.40 |
| Original Classification |
CO3 Chondrite |
| Fayalite (mol%): 20-38;Ferrosilite (mol%): 0-10 |
| B |
| A/B |
| All of these carbonaceous chondrites possess dull, black fusion crust with surface areas ranging from 10 to 100%. The matrices of these meteorites are fine grained and range in color from dark gray to brown to black. Inclusions are visible in most of them and vary in color from white to gray. |
| These meteorites are so similar that a single description suffices. The sections consist of abundant small (up to 1 mm) chondrules, chondrule fragments and mineral grains in a dark matrix. Metal and sulfide occur within and rimming the chondrules. Glass within chondrules appears to be very clear/fresh. CAIs are abundant in many sections (mostly Type A), and range in size up to 1 mm, many containing blue hibonite grains. At least one compound CAI was found. AOAs up to 1 mm exist, as well. Olivine ranges in composition from Fa0-80. Pyroxene analyses range from Fs0-44 (most from Fs0-13). These meteorites are somewhat terrestrially altered CO3 chondrites (likely type 3.0-3.2) and are probably members of the MIL 07182 pairing group. |
| The Miller Range (MIL) is the source of over 200 CO3 chondrites. After the 2003-04 and 2005-06 ANSMET seasons, a MIL 03377 pairing group was established with 5 members including the ~ 1.5 kg MIL 05013. Subsequent seasons (2007-08, 2009-10, 2011-12, 2013-14, and 2015-16) recovered many more, most of which were assigned to the large MIL 07099 pairing group. Some focused studies looking at all CO3s in this DCA have revealed that members of the MIL 03377 and MIL 07099 pairing groups have the same CRE age and overlapping Type II chondrule (FeO-rich) Cr2O3 contents. Additionally, Type II chondrule olivine Cr2O3 contents for the two member MIL 07673 pairing group overlaps completely with the other two large groups, and were recovered very closely to many of those samples as well. Given a decade of perspective and all this new information, we have combined the MIL 03377, MIL 07099, and MIL 07673 pairing groups into one (n=199). |
