Drill core CY-1, located in a down-welling region of the ancient hydrothermal system in the Troodos ophiolite, extends 474 m into the extrusive volcanic sequence. The bulk composition of CY-1 is compared with bulk compositions of surrounding locations, as well as in situ ocean crust to determine both variability within the CY-1 core and Cyprus, as well as how representative the CY-1 bulk composition is of in situ ocean crust. The bulk chemistry of the CY-1 drill core was calculated in two ways, first without considering secondary minerals or porosity, and second considering both porosity and the secondary minerals filling void space. Compared with fresh glass compositions, the volcanics of CY-1 exhibit an increase in MgO, K (sub 2) O, P (sub 2) O (sub 5) , Rb, Ni, Co, Th, and La, such trends were also evident in in-situ ocean crust at DSDP and ODP Sites 504B, 896A, 417A, and 418D. Decreases in SiO2 Al (sub 2) O (sub 3) , FeO (sub total) , CaO, Na (sub 2) O, and Sr concentration were apparent in the CY-1 drill hole as well as the DSDP and ODP drill sites.