Sentence:  It was a clear <WSD>steel</WSD>-blue day. The firmaments of air and sea were hardly separable in that all-pervading azure; only, the pensive air was transparently pure and soft, with a woman's look, and the robust and man-like sea heaved with long, strong, lingering swells, as Samson's chest in his sleep. 
Meaning of the word marked with <WSD> tags:  The gray hue of this metal; steel-gray, or steel blue.