We present the first analysis of Mariner 10 multispectral image data for the eastern limb and farside of the Moon. A new, rigorous calibration of these data is used that provides results that are consistent with independently derived data sets. From these newly calibrated data, a color ratio image (0.48/0.58 μm) is produced to show relative TiO2 abundances in mare units on the eastern limb and farside of the Moon. Our results indicate that the farside lunar mare deposits examined have TiO2 contents that are intermediate to low (2–5% TiO2) relative to mare deposits on the nearside. We find no evidence for areally extensive deposits of either very low titanium (VLT) or high to very high titanium (VHT) basalts in these portions of the Moon. Our findings support previous interpretations that the source regions for lunar mare basalts are laterally heterogeneous. Additionally, examination of highland units reveals a relatively blue region that corresponds with a previously proposed cryptomare, suggesting enhanced TiO2 for this unit. Finally, based on these Mariner 10 data, telescopic spectral data, Galileo multispectral image data, and lunar meteorite analyses we speculate that volcanism in farside mare deposits did not include high titanium basalts (> 8 wt %).