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Twins Above. This single japanese twin is from Fisher Mountain near Mt. Ida. This japanese twin on a cluster is from Burrough's Collier Creek mine near Mount Ida. Japanese twins have been scarce, but recovered from certain deposits in the Mount Ida area for the past 100 years. Only recently, have I heard from Ron Coleman of the discovery of a few Japanese twins from his mine near Jessieville. In 1996, while unpacking some recently mined specimens at the Tucson show, Ron came across a single Japanese twin. He recognized the specimen as one of the last ones dug, cleaned and packed to go to Arizona. So he separated it out, packed it back up, and shipped it back home. After he returned home from the show, he went into the mine and located the specific vein that specimen came from. Surprize! There was another Japanese twin just hanging on the vein wall, waiting for him to collect. Since then he had recovered several additional twins from that one vein. << Hi Mikey, Q. Can you define japan law twinning in quartz for me, what is the angle at which the crystals diverge, can you give a brief history of the discovery of this law and who first discribed it, also classic locations and how common or otherwise it is. John Weir, Whyalla, South Australia. >> A. Hi John, There are 4 related types of twins grouped under the name "Japanese twins." All are contact twins of two individuals, with the c-axes inclined (to each other) at the angle of 84 degrees 33 minutes. The common composition plane in all instances is (11-22) which reads as one one negative two two. In one of the 4 twin types this plane is a twin plane and in the other 3 it is a pseudotwin plane in that it only describes the angular relation between the axial system of the twinned parts. There are two general appearances to Japanese twins. The first is a twin form that looks like a V with the crystals appearing as either mildly tabular or distinctly prismatic individuals. The second is that of a butterfly or heart shape. Here the two individuals are both tabular. In the V twin, the contact area between the two crystals is relatively small, whereas with the butterfly, a larger area (when compared to the actual size of the crystals themselves) is the contact. Dana describes these as tabular appearing twins. The contact between the individuals composing a Japanese twin (called a composition plane) may be either planar or irregular, sometimes showing a zigzag pattern. This type of twinning was first recognized by a German mineralogist named Weiss in 1829 in crystals from La Gardette and the twin law became known as the La Gardette Law, Weiss' Law, and the {11-22} law. But several world class localities in Japan, including Otomezaka in Yamanashi Prefecture and Narushima in Nagasaki Prefecture have yielded such abundant and spectacular specimens that the name Japanese twin has reached acceptance in the literature. Many localities worldwide yield Japanese twins including several of the mines and sites in Arkansas, New York, Alaska, New Mexico and Arizona. Also, Switzerland, Brazil, the old USSR, and others too numerous to list. As far as local abundance in any deposit, it may range from rarely seen as in the Arkansas localities to a large percentage of the crystal present as in some of the Japanese localities. It all depends on the conditions when the crystals were forming. So, if you have a japanese twin from a site in Arkansas, it is scarce to say the least, but if you have one from New Mexico, the particular site yielded 100's if not 1000's of twinned specimens.   Mike H.   Ch 1, Page 7d Contact the authors of Rockhounding Arkansas Revised Feb 2000 ©Rockhounding Arkansas 1998 http://rockhoundingAR.com