saddle reef

from Wiktionary, Creative Commons Attribution/Share-Alike License.

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