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We present a homogeneous chemical abundance analysis of 16 elements in 190metal-poor Galactic halo stars (38 program and 152 literature objects). Thesample includes 171 stars with [Fe/H] < -2.5, of which 86 are extremely metalpoor, [Fe/H] < -3.0. Our program stars include ten new objects with [Fe/H] <-3.5. We identify a sample of "normal" metal-poor stars and measure the trendsbetween [X/Fe] and [Fe/H], as well as the dispersion about the mean trend forthis sample. Using this mean trend, we identify objects that are chemicallypeculiar relative to "normal" stars at the same metallicity. These chemicallyunusual stars include CEMP-no objects, one star with high [Si/Fe], another withhigh [Ba/Sr], and one with unusually low [X/Fe] for all elements heavier thanNa. The Sr and Ba abundances indicate that there may be two nucleosyntheticprocesses at lowest metallicity that are distinct from the main r-process.Finally, for many elements, we find a significant trend between [X/Fe] versusTeff which likely reflects non-LTE and/or 3D effects. Such trends demonstratethat care must be exercised when using abundance measurements in metal-poorstars to constrain chemical evolution and/or nucleosynthesis predictions.

The Most Metal-Poor Stars. II. Chemical Abundances of 190 Metal-Poor Stars Including 10 New Stars With [Fe/H] < -3.5