Frank Perham on Pseudo-Cubic Quartz Crystals

This find of quartz oddities was made at the Tamminen Mine, Greenwood, Maine, in the heart of Oxford County. The owner, Mr. Nestor Tamminen, and the author had suspected the location of these crystals, but due to drainage conditions, the area was difficult to work in. (ed. note: Then) Some work for feldspar in the pit during the summer of 1960 changed the water level and made the area workable.

This mine has long been recognized by collectors who come to Maine as one of the choice locations for rare and unusual minerals. The mine is located within a highly mineralized, lithia-rich pegmatite containing about fifteen separate mineral families and over forty varieties. The mineralizing solutions followed the hangingwall contacts of the pegmatite and the greater percent of the exotic minerals are found within twenty feet of the contact. The secondary mineralization was terminated with the permeating of the pegmatite by silica solutions causing pockets and vugs to form at random. Literally hundreds of pockets have been discovered in the course of mining, but rarely does any one pocket have many good quartz crystals. These crystals are unique in that rarely do you find a "common" crystal with single termination and long prisms. The crystals tend to be doubly terminated with short prisms, or to form in parallel groupings along the face of a larger crystal. Some very fine peduncled crystals have also been found in various pockets. One fact in the collectors favor is that in this location, most of the pockets were filled with a wet, sticky clay and during mining more crystals went over the dumps than were ever recovered.

The pseudo-cubic quartz crystals are not actually cubic, as the angle is not a right angle (ed note: 90°), but 85 degrees, 45 minutes (ed note: 89° 45'). When the crystals are oriented properly, it is easy to see all the faces and the side prisms, even though they are very small with respect to the enlarged faces. Until one gets the proper orientation though, it is difficult to see anything but a generally cubic block.

The actual removal of the pocket area had to be undertaken with great care because until we actually reached an opening, it was difficult to tell if one was there. The area of the crystals finally turned out to be a little over four feet long, with about twelve crystal-bearing pockets along the length of it. The mineralized area was bounded on one side by a huge block of feldspar with most of the pockets being contained in etched portions of the feldspar. The other side was solid massive quartz. For most of the four foot length, the pocket zone was lined with a light blue cleavelandite and we knew that if there were crystals, they would be in this cleavelandite zone. To remove the rock, we drilled short holes about two feet from the cleavelandite and blasted lightly. With a pinch bar, we pried out the rock hoping for a cavity of quartz crystals.

	The first pocket showed as just a ball of mud. When we worked this mud through our fingers, we felt the crystals within. This was it! From then on, wild horses couldn't have pried us from the hole, as we picked out masses of brown mud and worked them through our fingers to extract the treasures. The first crystals we extracted were only doubly terminated and in the usual light transparent smoky color. Most of these crystals were one-quarter to one-half inch long, which is the average size for individual crystals in this pit. After we had progressed aways, some of the crystals began to be cubic in general form and finally we hit one chamber filled with mud that must have yielded close to two hundred crystals in various stages of cubic nature. We finally cleaned out the pocket area at dusk and proceeded to Mr. Tamminen's home where we cleaned our find. Out of 300-400 crystals, we had about 100 cubic, and of these, about twenty-five were nice ones with one beauty measuring 1 and five-eights inches on one side. Even those crystals which were not cubic, were unusual in that they contained liquid inclusions with movable bubbles. I, for one, slept with visions of quartz crystals that night.	Pseudo-cubic quartz crystals, showing comparative sizes. (Editor's note: We apologize for the poor image. Searching for a better copy.
	Mr. and Mrs. Tamminen have a very nice mineral collection of quartz crystals in odd forms and also of the other pegmatite minerals found in their mine and the general vicinity. They like to meet other "rockhounds" and swap minerals, and if you should be lucky enough to hit the right day, you might even be able to get one of the cubics for your collection without the "work" of digging in the mine dumps for it. (editor's note: Mr. and Mrs. Tamminen are now deceased, and Mr. Perham is now the owner and miner of the quarry.)
	editor's note: I was able to find specimens to photograph, although not from the find described by Mr. Perham above. These crystals do represent what was found though. All are 2.5X life size. Crystal A - same crystal, rotated 180° Crystal B - same as left image of A, but photographed to show the phantom growth internally. Crystal C - a perfect cube Crystal D - same crystal, rotated 90°

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