Although not a typical mainstream gemstone, zoisite has something to offer everyone, especially for gemstone and jewelry lovers. In the right environment, zoisite is found in the form of either prismatic crystals in veins or massive mineral formations. Zoisite can come in a range of different colors — brown, grey, yellow, blue, violet, green, pink, as well as colorless, depending on its inclusions.
It has a vitreous luster but can sometimes be granular or sugary too. It can be either translucent or transparent, and its hardness on the Mohs scale is 6. Zoisite was discovered and described at the end of the 18 th and the beginning of the 19 th centuries.
Zois had just sent Werner zoisite specimens from Saualpe, Carinthia. The specimens themselves are presumed to have been mined in There are several types of zoisite you might have heard of. The differences between them are based mostly on their color, chemical composition, and mining locations.
Here are the ones to note:. The royal blue of tanzanite. See these here. It is a transparent blue zoisite and is the second most sought after blue gemstone in the world after sapphire. The two minerals are dimorphs - they share the same chemical composition but have a different crystal structure. The minerals have extremely similar physical properties and can be very difficult to tell apart in hand specimens unless the specimens are well-formed crystals.
Clinozoisite forms a solid solution series with the mineral epidote in which iron can substitute for aluminum. Zoisite: Shown above are 4 specimens of zoisite in unusual colors. Top row: pink and yellow crystals with orthorhombic crystal habit.
Bottom row: left a parti-colored specimen with shades of green and pink in the same crystal; right a blue-green crystal with nice termination. Photos courtesy of The Rare Gemstone Company. Zoisite and clinozoisite are minerals that are usually found in small quantities. They have not been used in significant amounts by industry. Transparent and colorful specimens of both minerals have been used as gemstones.
Zoisite is the mineral of some very diverse gem materials, one being the extremely popular tanzanite which was discovered in the s and immediately became one of the world's most popular gems.
Tanzanite is the most famous zoisite. It is a transparent blue zoisite that is colored by the presence of vanadium. Some blue zoisite is found naturally, but most is produced by heat-treating brown zoisite. The heat changes the oxidation state of vanadium to produce the blue color. Tanzanite is the second most popular blue stone, after sapphire. Originally found in Norway, Thulite is named after the mythical region of Thule, which many identify as Norway.
See the gemstone Thulite for additional information, and see also Clinothulite. Let us know how we can update this page Click for more details. We strive for accurate content and locality information.
If you feel any of the content is incorrect, or if you feel we are missing vital locality information, please fill out the form below so we can update the site. If you are requesting a locality be added, please only include significant locality occurences for the mineral. About Minerals. Link Directory Donations Mobile Site. Chemical Formula. Basic calcium aluminum silicate. Gray, beige, yellow, brown, green, blue, purple, pink, red. Transparent forms are strongly pleochroic. Crystal System.
Crystal Forms and Aggregates. As prismatic and sometimes elongated crystals, which are often deeply striated lengthwise. Crystals are occasionally pointed or wedge-shaped.
Habits include bladed , columnar , reticulated , radiating , fibrous , and massive. Transparent to translucent. Quartz : pure SiO2 is colorless, not normally used as a gem. Citrine transparent, shades of orange Citrine yellow-orange-brown color may be zoned the color is due to the presence of Fe, which is also the impurity present in amethyst. Rose quartz has rose-pink color the color is often due to the element Titanium Ti used for beads etc.
Green quartz Milky quartz milky appearance due to inclusions often of fluid often associated with gold deposits - used as a gem mainly if gold present. Rutilated quartz is normally clear quartz that contains fine, often oriented, rutile crystals. Rutilated quartz common in jewelry The term "venus hair" refers to fine red rutile needles Note the orientations of the rutile needles.
Tourmaline and other inclusions examples of quartz containing tourmaline and Fe-oxide fine tourmaline needles a second example of green tourmaline in quartz other inclusions can involve minerals possibly rutile and open tubes, for example: at low magnification these features make interesting patterns, the three dimensional nature of these needles is quite apparent. Chatoyant quartz due to the presence of needles of asbestos etc. Other fibrous varieties, including agate and chrysophrase are discussed in later lectures Adventurine : green quartz containing platy inclusions of mica; can be used as a substitute for jade; used in beads etc.
Quartz can also contain inclusions of trapped fluid that may contain mineral precipitates and gas bubbles ' fluid inclusions ' [Note the bubble of liquid and gas in this image is round.
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