A thin polished slice of agate (silica), seen in transient light, exhibits pinnacles and dendritic patterns resulting from the precipitation of manganese and iron oxides. These sophisticated "landscape agates" are much sought after by collectors, cut and polished as they are into thin little cabochons or oval slices; an art mastered by the best professionals of the trade only. The agate is from Espumoso, Brazil, a region famed for its 'landscape' agates. Actual width of specimen is 35 mm