The orthopyroxenite ALH 84001 was recently reclassified by Mittlefehldt  as a martian meteorite. We analyzed several aliquots from a total of 1.7 g of split 40 for major and trace elements (Table 1). Mineral compositions were determined by SEM-EDS analysis on thin section ALH 84001,89, which does not come from the same split as our bulk sample. Nevertheless, the compositions found are practically identical to those reported by , showing that ALH 84001 is a rather homogeneous rock with regard to the composition of the minerals, although their relative proportions may vary (see below).
The chemical composition confirms ALH 84001 as a martian meteorite and not as a diogenite. A typical feature for the HED meteorites is their low abundances in volatile, moderately volatile, and siderophile elements compared to terrestrial and martian rocks. An exception is S: HEDs contain between 1000 and 5000 ppm S. Compared to the 3900 ppm S in the diogenite Johnstown, the 108 ppm S in ALH 84001,40 is very low, but matches the S values for the nakhlites (300 ppm) and Chassigny (120 ppm). The exposure age of 14 ± 2 m.y.  indicates also a relationship to nakhlites and Chassigny. Furthermore, the high abundance of Zn, which is enriched by a factor of 160 relative to Johnstown, is typical for the martian rocks. In contrast to ordinary chondrites, not all the Zn is found in the chromite; its content of 0.1% ZnO accounts for only 20% of the Zn; the rest must be contained in the silicates. Cobalt is enriched by a factor of 4 compared to Johnstown and fits well into the correlation of Co vs. MgO + FeO found for the other SNCs. Compared to ALH 84001,20 analyzed by  our sample ,40 has a higher Na and K content, indicating about twice the amount of maskelynite. The Na/K ratio of 6.6 in our sample is close to that of 6.4 found in maskelynite. Our REE pattern is similar to that of split 20 , but with a lower negative Eu anomaly (Fig. 1), in agreement with the higher maskelynite content. Using the mineral composition in ALH 84001,89 and our bulk Na, Cr, C, P, and S values, we obtain for the bulk sample 2.0% maskelynite, 1.9% chromite, 0.46% carbonate, 0.031% phosphate, and 0.021% pyrite (the rest being opx with traces of cpx). The phosphate crystallizing from a residual liquid could be responsible for the enrichment of the LREE compared to the OPX separate of Johnstown ; see Fig. 1.
References:  Mittlefehldt D. W. (1994) Meteoritics, 29, 214-221.  Miura Y. N. et al. (1994) LPS XXV, 919-920.  Floran R. J. et al. (1981) GCA, 45, 2385-2391.