Whitestone

"blackguardise the whitestone ever hurtleturtled out of heaven"

Refers to the Black Stone, which is displayed at the Kaaba (cube-house) within the Great Mosque in Mecca. "Dating from pre-Islamic times as a heavenly relic, this stone is venerated and ritually kissed." (wikipedia)

According to legend, the stone fell from heaven and was originally white, but was changed to black by the sins of the world.