Abstract-A stony meteorite fell at Itawa Bhopji, Rajasthan, India on 2000 May 30. This is the fifth recorded fall in a small area of Rajasthan during the past decade. The meteorite is an ordinary chondrite with light clasts in a dark matrix, consisting of a mixture of equilibrated (mainly type 5) and unequilibrated components. Olivine is Fa24-26 and pyroxene FS 20-22 but, within the unequilibrated components, olivine (Fa5-29) and low calcium pyroxene (FS 5-37) are highly variable. Based on petrographic studies and chemical analyses, it is classified as L(3-5) regolith breccia. Studies of various cosmogenic records, including several gamma-emitting radionuclides varying in half-life from 5.6 day 52Mn to 0.73 Ma 26AI, tracks and rare gases have been carried out. The exposure age of the meteorite is estimated from cosmogenic components ofrare gases to be 19.6 Ma. The track density varies by a factor of -3 (from 4 to 12 x 10 6/cm2) within the meteorite, indicating a preatmospheric body of -9 ern radius (corresponding to a meteoroid mass of -11 kg) and small ablation (1.5 to 3.6 ern). Trapped components in various rare gases are high and the solar component is present in the dark portion of the meteorite. Large excess of neutron-produced 82Kr and 128Xe in both the light and the dark lithology but very low 60Co, indicating low neutron fluxes received by the meteoroid in the interplanetary space, are clear signatures of an additional irradiation on the parent body.

Abstract-Two stones that fell near Piplia Kalan on 1996 June 20 are identified as Ca-rich achondrites belonging to the eucrite group. The conditions of their fall are described. The petrographic description, texture and chemical composition, the elemental ratios, particularly K/La and Yb/Sc, and relatively flat rare-earth-element (REE) patterns (6-8x chondrite) of bulk samples without any significant Eu anomaly all agree with the characteristic values found in eucrites. A feldspar-rich fraction shows a significant positive Eu anomaly. The presence of several different lithologies and clasts indicates that it is a texturally diverse breccia, and the chemical analysis suggests that it belongs to the noncumulate group of eucrites falling in the Nuevo Laredo trend.

We report the presence of a 3-5 cm thick loose fragmental layer in the Siliceous Earth at Matti ka Gol in the Barmer basin of Rajasthan. Petrographic, chemical and mineralogical study reveals the presence of abundant volcanic debris such as glass shards, agglutinates, hollow spheroids, kinked biotites, feldspars showing oscillatory zoning, olivines, ilmenite and native iron. The presence of similar particles in the whole section suggests that the Siliceous Earth is a volcanic ash. Stratigraphic correlation, palynological and microvertebrate data suggest that the Siliceous Earth may have deposited over a short span of time during the Upper Cretaceous to Lower Palaeocene. In view of the possibility that this section may contain K/T impact debris, we looked for grains having impact signatures. Some patches of the Siliceous Earth of Bariyara show the presence of Ni-rich (> 0.5%) vesicular glasses, sanidine spherules, magnesioferrite crystals, soot, etc., but because of their low abundance, it is not possible to establish if they are volcanic, micrometeorite ablation products or a part of the K/T impact ejecta.

Abstract-Cosmogenic radionuclides, particle tracks and rare gases have been measured in two fragments of the Piplia Kalan eucrite that fell in Rajasthan, India on 1996 June 20. The cosmic-ray exposure age of the meteorite is calculated to be 23 Ma, which is similar to ages of some other eucrites. The track density in feldspars and pyroxenes varies between 0. 2 x lo6 to -4. 5 x lo6 cm-2. The mass ablation of the meteorite, based on the distribution of track density in near-surface samples of the two fragments, is calculated to be -75%, which corresponds to an entry velocity of -17 kmls. The orbital parameters of the eucrite have been computed from the radiant of the meteor trail and the geocentric velocity. The best estimates are a = 2. 47 AU, e = 0. 62 and i = 7. 54", which is similar to the orbital elements of other meteorites, most of which have been inferred to originate within 2. 6 AU of the Sun. The activity of the radionuclide 26A1 agrees with the expected production rate; whereas the shortlived radionuclides 22Na, 54Mn, 46Sc etc. have levels that are consistent with the galactic cosmic-ray fluxes that are expected during the solar minimum period before the time of fall. All the cosmogenic effects ( i e . , radio-and stable-nuclides and particle tracks) are consistent with the meteoroid having had a simple, one-stage exposure history in interplanetary space. Lower radiogenic ages of U, Th-He (0.7 Ga) and K-Ar (3.6 Ga) indicate severe losses of 4He and 40Ar, as observed in most eucrites. A Pu-Xe age, concordant with Angra dos Reis, shows that Piplia belongs to the "old" eucrite group.

Abstract-The Lohawat meteorite is a texturally heterogeneous breccia having a variety of mineral and lithic fragments. Among mineral fragments, pyroxenes show a wide range of composition WOO,^^^^, 1 7 E n 0 , 3 7~. 7 8 F S 0 ,~~~) . 6 0 ) whereas plagioclase is anorthitic (An0.92Abo.070ro.007). Abundant rounded "chondrule-like" objects ranging in size up to -7 mm, some with concentric layering, have been observed. Petrographic features, trace element composition and rare earth element patterns show the presence of eucritic and diogenitic components confirming that it is a typical howardite. Cosmogenic tracks, rare gases (He, Ne, and Ar) and radionuclides (22Na and 26A1) were measured.Track density in olivine and plagioclase varies between 0.7 to 6 x 106/cm2. 38Ar exposure age is estimated to be -1 10 Ma, being the highest among howardites. The track production rates correspond to ablation of 9 to 15 cm, implying a radius for its preatmospheric size of -27 cm. 22Na /26AI = 1, as expected from the production models and solar modulation of galactic cosmic-ray fluxes before its fall, suggesting that the meteoroid did not undergo any fragmentation during the past -2 Ma in interplanetary space. The radiogenic age based on K-Ar method is 4.3 Ga while the U-Th-4He age is 3.3 Ga indicating partial loss of He.