NWA 305, The EL3 Chondrite
A 210 g weathered meteorite was purchased by meteorite dealer Dean Bessey from Erfoud, Morocco during December of 2000. This meteorite was found by a Berber nomad, possibly in North West Africa but the find location is not known.
was cutting material about a year ago for ebay and cut into this stone. I looked
at it and thought "Wow, that is certainly a nice LL3" Bessey recalls. The
meteorite fell apart while being cut and only about 160 grams was usable. Large
amounts of the meteorite were used in making thin sections. A 34.7 gram piece,
along with a thin section were submitted to the Russian Academy of Sciences for
classification, with several other meteorites. The preliminary analysis
determined that it was an Enstatite 3 chondrite, with a shock stage of S2 and a
weathering grade of W3. All Enstatite chondrites are considered rare and this
one is one of the rarest. After cutting loss, thin section samples, and donation
of type specimen, there is less then 100 grams of this meteorite available to
Enstatite chondrites are separated into one of two groups. A high-nickel and high-siderophile group, the EH's, or a low-nickel and low-siderophile, the EL's. Chondrules from both the EH's and EL's were formed from a similar material in the same region of space. During accretion, they underwent a size sorting resulting in the larger chondrules (the EL's) being buried more deeply than the smaller chondrules (the EH's). The EH material being more exposed, cooled faster and have lower values on many metallic minerals when compared to the EL's. Testing shows that minerals, such as nickel in schreibersite, titanium content in troilite and manganese content in daubreelite, are all found in lower levels in EH's when compared with EL's.
The Chondrules are visually different in the two E chondrites. The EL chondrules average twice the size of the EH's. Slices of NWA 305 show the larger chondrules present. It is no wonder that Dean Bessey thought he had found an LL3. NWA 305 chondrules can make an LL3.1 such as Krymka jealous.
From the classification data presented by the Russian Academy of Sciences, showing EL values, and the large diameter of its chondrules, NWA 305 is an EL3 chondrite. The only EL3 outside of Antarctica.