Fig. 4: In-situ analysis points on gabbroic stone (“black granite”) used as exterior wall cladding of the Osaka Gas Building.

A Overall view of the building. The red dotted line indicates the area shown in (B). B Close-up view of the south façade, with numbered points indicating the measurement locations: (1) an area with a visible schlieren structure, (2) an area with a uniform massive structure, and (3) an area that appears to have been repaired. C In situ pXRF measurement on the cladding stone, where a schlieren structure is visible.