Tunellite is a rare strontium borate hydrate found as a secondary mineral in borate deposits and this is a large and extremely significant piece for the species! This Tunellite specimen consists of numerous, translucent, pale gray-blue crystals in perfect, slightly staggered, parallel growth and all of the crystals exhibit a wonderful pearlescent luster. The crystals are almost diamond shaped and viewing the piece along its side, the lamellar character of the mineral resulting from its perfect (100) cleavage can be seen. Faces and edges of the composite monoclinic crystal are really well formed and pronounced resulting in an exceptional example from this classic and highly productive borate mine in the Death Valley area of California. Although it is a borate, Tunellite is very stable and won't decrepitate. This is certainly one of the best pieces we've seen for the species and few specimens were saved as they came out. Specimens of this quality are very hard to obtain today. ex Bob Reynolds collection, and he got it directly from the collection of the man who collected this and nearly all others, Jim Minette, former manager at the Boron mine. Bob Reynolds was the curator of the San Bernardino County Museum and a longtime California specialist; as well as a trading partner with Jim Minette, the Boron mine manager who collected these in the 1960s and 1970s. Boron was famous for this material and produced the best of the species for this material. It has not been equaled by crystals from any other locality, despite huge borate deposits elsewhere in the world, for reasons that are not entirely clear.