Wiktionary
saddle reef
n. 1 (context mineralogy English) A mineral deposit associated with the crest of an anticline fold and following the bedding planes, usually found in vertical succession, especially the gold-bearing quartz veins of Australia. 2 (context Australia English) A saddle-shaped bedded mineral vein in the form of an anticline or a syncline (an inverted saddle). 3 (context mineralogy English) An opening at the crest of a sharp fold in sedimentary rocks, occupied by ore.