200 Lemon Metallic / Metallic Green
BrickLink: Metallic Green (includes other colors too)
Peeron: Metallic Green (ditto)
This color was used in 2001 for a technic hose (sort of, see comments) and in 2003 for Bionicle masks. No solid plastic parts are known in this color. This is a pearly color, NOT the metallic-coated green used for technic panels.