Specimen Notes
Occurrence - The Ulrichite occurs in vugs and narrow seams in a course grained Granite, which in turn occurs on a fine granite host rock. The boundary between the two granites is sharply defined. The course grained granite has numerous vugs and open seams between crystals. No such openings can be seen in the fine grained granite.
No Ulrichite can be seen occurring on or in the fine grained granite. The lack of occurrance in the fine grained granite, and only in open areas of the course grained granite, indicates it is a secondary mineral deposited from solution.
Both of the granites are primarily quartz, the course grained granite, containing the Ulrichite, has a large iron content, giving it its green color. Both granites contain Muscovite (mica), with the crystals of this mineral being very much larger in the course grained granite. Image (001c) shows the Ulrichite on iron oxide coated quartz next to rose quartz. Between the two is a deposit of Goethite that was formed by hydrothermal action on Siderite.It is likely that the Ulrichite was deposited during this hydrothermal action.
Crystals - The Ulrichite occurs as long blades with termination bevels. Many of the crystals appear to be squared off, but closer examination shows otherwise. The crystals closely resemble the generic Monoclinic - Prismatic form, only greatly elongated.
The [100] face may or may not be present. Due to the size of the crystals, its presence is difficult to discern. It may be the cause of the squared-off appearing terminations seen on many of the crystals. The [100] axis is not the apparent (cross-sectional) axis of the crystal, and differing from it greatly, as can be best seen in the crystal model of Ulrichite.
Habit - The crystals form in radial clusters that radiate from a single point, or locus. Only a few crystals originate from each radial locus, giving a very open structure to each cluster. A single cluster may be seen on the center-right of image (001b). Many growth loci may occur close together, resulting in a tangled mass of crystals, as seen in (001a) and the center-left of (001b).
Lone crystals do form, as seen in image (001a), it is not the usual occurrance for Ulrichite. It is suspected that these may have broken loose from clusters and continued to grow on their own.
Ulrichite's growth on Quartz (silica) follows the hot radicals theory of Uranyl crystal occurrance. Lacking a -1 valence radical, or anion, it can form directly on silica/silicate rock.
Diaphaneity and Luster - The crystals appear to be somewhat translucent to opaque. The luster is vitreous and highly reflective.
The color of the Ulrichite is a light, pale green with a tint of yellow.
Radioactivity - The radioactivity of the specimen is quite low, lower than expected for a granite rock. While Ulrichite is itself highly radioactive, it is not present in the specimen to any great quantity. The low radioactivity supports the belief that the Ulrichite was transported to the granite.
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Special Notes - The specimen is both scientificly and historically significant as it was found at the same location as the type specimens' occurrence. The mineral's discoverer, Anthony Fraser, is an Australian mineral collector and gold dealer. He first found Ulrichite when 17 years old on a field trip with the local gem and mineral club, the Bendigo Gem Club, of which he was the youngest member by around 25 years. At the time it was the first new species to be discovered in Victoria in 107 years. The previous species being Maldonite (Au2Bi), this was decribed by the government mineralogist George Ulrich - thus Ulrichite.
This specimen of Ulrichite is from the type pocket, and was found with the type specimens, and is from the discoverer's collection. It is one of the largest and most prominent that was collected. Some smaller pieces collected with it are pictured in the Museum of Victoria book The Phosphates of Victoria. The specimen resided in Fraser's personal collection until recently when he parted with it. It is one of the richest known examples of the species, as it contains at least three (3) separate vugs of protected crystals in a granitic matrix.
The Lake Boga Quarry now is pretty much exausted of Ulrichite. The one small fault zone which yeilded all the material has been totally worked through and this material is now spread over many miles of the district's roads! The last specimens are believed to have come out more than 8 years ago (before 1997). The specimen here was collected by Anthony Fraser nearly 20 years ago (circa 1985).
Image (Boga1) shows the productive area on the bottom left hand side of the image (the corner in front of the two vehicles). The second image (Boga2) is a close-up, on ground level, of this corner of (Boga1). (note the rock hammer in the center of the image for scale). The main mineralization appeared to be associated with the intersection of the two major vertical right angle faults which are evident in the image.
My thanks to Anthony Fraser for the above information on Ulrichite, the Lake Boga granite quarry images, and the discovery of Ulrichite.
Specimen Physical Properties
| Specimen Size: |
5.6 cm |
4.3 cm |
4.1 cm |
| Weight: |
117.14 grams |
(includes mount) |
| g-Radiation Level: |
22 cmp |
22 msieverts per hour |
background: 20 cpm |
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