Sample 15388
15388 Porphyritic Pigeonite Basalt 9.0 grams
Section titled “15388 Porphyritic Pigeonite Basalt 9.0 grams”
Figure 1: Photo of 15388. Sample is 2 cm. NASA S71-49197.
Introduction
Section titled “Introduction”Lunar sample 15388 was collected as a rake sample from the rim of Spur Crater (part way up the Apennine Front). It is a pigeonite basalt with long pyroxene crystals. It has not been dated.
Petrography
Section titled “Petrography”Dowty et al. (1973) and Ryder (1985) describe 15388 as a coarse-grained, mare basalt with an apparent abundance of plagioclase (figure 2). However, Nehru et al. (1974), Ryder (1989) and Ryder and Steele (1987) suggest that it may be significantly different from the majority of the Apollo 15 basalts and may be unique.
Mineralogy
Section titled “Mineralogy”Olivine: none
Pyroxene: Dowty et al. (1973) reported the pyroxene composition (figure 4).
Plagioclase: Plagioclase is calcic (An90-95).
Ilmenite: Nehru et al. (1974) studied the opaque minerals in 15388.
Chemistry
Section titled “Chemistry”The composition of 15388 is low in FeO and high in TiO2 (figure 5), but sample size was small for such a coarse grained-sample.
Other Studies
Section titled “Other Studies”Bhandari et al. (1973) determined the density of solar flare tracks in the surface of 15388 and give a “suntan” exposure age of less than 1 m.y.
Processing
Section titled “Processing”15388 has been sawn to create splits.
Mineralogical Mode of 15388
Section titled “Mineralogical Mode of 15388”| Dowty et al. 1973 | |
|---|---|
| Olivine | |
| Pyroxene | 51 |
| Plagioclase | 36 |
| Opaque | 6 |
| Silica | 0.5 |
Figure 2: Photomicrographs of thin section 15388,11 by C Meyer @ 50 x (bottom is crossed nicols).
Figure 3: Photomicrograph of matrix of 15388 (from Dowty et al. 1973).
Figure 4: Composition of pyroxene in 15388 (from Dowty et al. 1973).
Figure 5: Composition of 15388 compared with that of other lunar basalt types.
Figure 6: Normalized rare-earth-element diagram for 15388.
Figure 7: Photo of 15388 after first wire saw cut. NASA S71-59082.
References for 15388
Section titled “References for 15388”Bhandari N., Goswami J. and Lal D. (1973) Surface irradiation and evolution of the lunar regolith. Proc. 4th Lunar Sci. Conf. 2275-2290.
Butler P. (1971) Lunar Sample Catalog, Apollo 15. Curators’ Office, MSC 03209
Dowty E., Prinz M. and Keil K. (1973b) Composition, mineralogy, and petrology of 28 mare basalts from Apollo 15 rake samples. Proc. 4th Lunar Sci. Conf. 423-444.
Dowty E., Keil K. and Prinz M. (1974c) Lunar pyroxenephyric basalts: Crystallization under supercooled conditions. J. Petrology 15, 419-453.
Dowty E., Conrad G.H., Green J.A., Hlava P.F., Keil K., Moore R.B., Nehru C.E. and Prinz M. (1973a) Catalog of Apollo 15 rake samples from stations 2 (St. George), 7 (Spur Crater) and 9a (Hadley Rille). Inst. Meteoritics Spec. Publ. No 11, 51-73. Univ. New Mex. ABQ.
Laul J.C. and Schmitt R.A. (1973b) Chemical composition of Apollo 15, 16, and 17 samples. Proc. 4th Lunar Sci. Conf. 1349-1367.
LSPET (1972a) The Apollo 15 lunar samples: A preliminary description. Science 175, 363-375.
LSPET (1972b) Preliminary examination of lunar samples. Apollo 15 Preliminary Science Report. NASA SP-289, 6- 1—6-28.
Ma M.-S., Murali A.V. and Schmitt R.A. (1976) Chemical constraints for mare basalt genesis. Proc. 7th Lunar Sci. Conf. 1673-1695.
Nehru C.E., Prinz M., Dowty E. and Keil K. (1974) Spinelgroup minerals and ilmenite in Apollo 15 rake samples. Am. Mineral. 59, 1220-1235.
Ryder G. (1985) Catalog of Apollo 15 Rocks (three volumes). Curatoial Branch Pub. # 72, JSC#20787
Ryder G. (1989) Mare basalts on the Apennine Front and the Mare Stratigraphy of the Apollo 15 landing site. Proc. 19th Lunar Planet. Sci. Conf. 43-50.
Ryder G. and Steele A. (1988) Chemical dispersion among Apollo 15 olivine-normative mare basalts. Proc. 18th Lunar Planet. Sci. 273-282. Lunar Planetary Institute, Houston.
Swann G.A., Hait M.H., Schaber G.C., Freeman V.L., Ulrich G.E., Wolfe E.W., Reed V.S. and Sutton R.L. (1971b) Preliminary description of Apollo 15 sample environments. U.S.G.S. Interagency report: 36. pp219 with maps
Swann G.A., Bailey N.G., Batson R.M., Freeman V.L., Hait M.H., Head J.W., Holt H.E., Howard K.A., Irwin J.B., Larson K.B., Muehlberger W.R., Reed V.S., Rennilson J.J., Schaber G.G., Scott D.R., Silver L.T., Sutton R.L., Ulrich G.E., Wilshire H.G. and Wolfe E.W. (1972) 5. Preliminary Geologic Investigation of the Apollo 15 landing site. In Apollo 15 Preliminary Science Rpt. NASA SP-289. pages 5-1-112.
Table 1. Chemical composition of 15388.
| reference Laul73 weight SiO2 % TiO2 Al2O3 FeO MnO MgO CaO Na2O K2O P2O5 S % | Ma 76 | Ryder88 | Dowty73 | |||||
|---|---|---|---|---|---|---|---|---|
| 1.1 15.4 15.1 0.2 10 11.7 0.43 0.024 | 5.1 12.8 17.6 0.22 7.7 10.5 0.42 0.032 | (a) 8 (a) | 628 mg 44.2 (a) 5.91 (a) 11.1 (a) 19.1 (a) 0.35 (a) 10.2 (a) 0.32 0.06 | (b) 45.7 (b) 2.57 (b) 10.9 (b) 17.2 (b) 0.2 (b) 10.1 (b) 9.7 (b) 0.39 (b) 0.02 | (c ) (c ) (c ) (c ) (c ) (c ) (c ) (c ) (c ) | |||
| sum Sc ppm | 42 | 43 | (a) 48.6 | (a) | ||||
| V Cr Co Ni | 180 2700 37 | 150 2350 27 | (a) | (a) 2323 (a) 41.9 | (a) | (a) 2000 | (c ) | |
| Cu Zn Ga Ge ppb As Se Rb Sr Y Zr Nb Mo Ru Rh Pd ppb Ag ppb Cd ppb In ppb Sn ppb Sb ppb Te ppb Cs ppm Ba La Ce Pr Nd | 1.2 4.2 | 29 1.6 | (a) (a) 5 | (a) 1.75 | (a) (a) | |||
| Sm Eu | 1.2 0.89 | 1.5 0.91 | (a) 1.89 (a) 0.841 | (a) (a) | ||||
| Gd Tb Dy Ho Er | 0.3 2.5 | 0.36 3.4 | (a) | (a) 0.58 | (a) | |||
| Tm Yb Lu Hf Ta W ppb Re ppb Os ppb Ir ppb Pt ppb | 1.6 0.22 0.9 | 1.6 0.29 1.2 | (a) 1.98 (a) 0.3 (a) 1.82 | (a) (a) (a) | ||||
| Au ppb Th ppm | 0.43 | (a) | ||||||
| U ppm |
technique: (a) INAA, (b) fused bead elec. Probe, (c ) broad beam elec. Probe