Smooth surfaced, non-faceted cuts of gemstones, in any shape.

Cabochons Index

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Rainbow Calsilica (Cal Silica) - Mohs 3-4

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Rainbow Calsilica is a rainbow colored stone from Chihuahua, Mexico. It does not take a super high shine, which makes it a natural with casual clothing - especially jeans. It is right at home with dressier outfits as well and coordinates with a lot of colors. Although I tend to buy striped material, it is also found in big, random patterns as well. It just depends on whether it is cut with the stripes or across the stripes.

Calsilica appears to be a natural stone, although there was controversy when it was first introduced to the market and that information still lingers. Testing was done by various labs to determine that is was not a man-made product. However, even if it turns out to be an elaborate hoax and it is a manmade product, it is a fun stone that gets lots of comments. The greens and blues in the stones are calcite allophane clay. The other colors are silica tinted by trace metals to create reds, browns, tans, yellows, whites, etc. Calsilica is stabilized in the same manner that turquoise is stabilized.

Rhodochrosite - Mohs 4

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A soft stone that can be brittle, it is prized for its lovely pink-rose color and white markings. Transparent red crystals (no impurities) do occur, but are rare.

Rhodochrosite is a manganese carbonate, a minor ore of manganese, and gets its pink color from the manganese. The white patterns come from other minerals, such as calcites. It often forms in stalactites and stalagmites in old mines. It is found many places, especially in North and South America and Africa, but I find a lot of what I have bought has come from Peru or Argentina. The rhodochrosite I have purchased from Peru has some of the most interesting "bulls-eyes" while that from Argentina often has interesting soft grey patterns in it.

Rhodonite - Mohs 5.5-6.5

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A darker, rose-red or raspberry color that often has black dendritic inclusions of manganese oxide. Transparent crystals do occur, but are very rare. Rhodonite is a manganese iron magnesium calcium silicate, a minor ore of manganese.

Rhodonite is found many places around the world. The pieces in the picture above are all from Australia and were called "imperial rhodonite" by the lapidary I purchased them from.

Rhodonite-Rhodochrosite

Refers to a stone composed of both rhodonite and rhodochrosite. The interplay of the darker raspberry colored rhodonite and the pink and white of the rhodochrosite can be quite striking - especially when accented with black.

Ruby-Zoisite (Ruby in Zoisite) (Anyolite) - Mohs 6.5

Rutilated Quartz

Clear quartz with inclusions of golden rutile needles.

Rutile

Titanium oxide (a titanium ore). Microscopic inclusions of rutile in quartz, tourmaline, ruby, sapphire and other gemstones produces effects such as cat’s eye (chatoyancy) and stars (asterism). A beautiful stone produced by large inclusions of golden rutile needles in clear quartz is called Rutilated Quartz.

Sagenite

Depending on who is using the term, they could be referring to Sagenitic Agate or Rutilated Quartz. While rutilated quartz may be a type of sagenite, it has a very defined type of inclusion - rutile. Sagenitic agate, on the other hand, seems to mean there can be various kinds of inclusions, as long as they are needle-like. (Agate is a type of cryptocrystalline quartz.)

Sagenitic Agate (Sagenite)

Agate having needle-like mineral growths. These hair like filaments are often arranged in fans or sunbursts. The inclusions come in a wide array of colors. Inclusions occur where iron oxide, manganese oxide, or other oxides are present when the agate is formed. The oxide minerals grow in the agate when it is in a liquid or gelatinous state. The inclusions grow and are supported by this liquid medium. Sagenite seems to be named based on the geographic location it came from.

Serpentine (Serpentinite, Serpentine Rock) - Mohs 5

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Serpentine refers to a group of predominately green minerals. Most people will call rock created from these minerals serpentine, but you will also see it refered to as serpentine rock and serpentinite. Serpentine is popular for carving and sculpting.

While serpentine is normally some shade of green, it can also be yellow, yellow-green, green-blue, blue, brown, red, black, or white. The color can be fairly uniform or various colors can be mixed together in blotches, streaks, or other patterns. It can be translucent to opaque and may have inclusions. I particularly like sculptures I have seen done in dark greens, but I prefer the lighter shades for jewelry.

There are many varieties of serpentine and not many lapidaries will distinquish the stone they are cutting further than serpentine. If a lapidary it cutting it, it is normally in the 4-5 hardness range, although serpentine can be softer.

The kinds of serpentine used for jewelry normally are of the antigorite type, including those called bowenite and williamsite.

Sodalite - Mohs 5.5-6

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Sodalite, as most people are familiar with it, is a dark to light blue stone that often has white veins of calcite in it. It can be a component of lapis lazuli and can have a similar appearance, but the tone of blue is different and it does not have any pyrite flecks. To me, sodalite is normally more of a blue-black than lapis.

Sodalite does come in other colors, including grays/whites, green, yellow, and pink.

Sodalite Group - a group of related minerals named for the most common member, sodalite. Also includes Hauyne, Lazurite, Nosean.

Stalactite, Stalagmite

Mineral formations found on the ceilings and floors of caves. Stalactites are icicle-shaped. They form as minerals precipitate from groundwater seeping through the roof of the cave. As the water falls to the floor of the cave, minerals also precipitate and accumulate there. The mineral deposits on the floor grow upward and are called stalagmites. As they grow, stalactites and stalagmites can meet and create giant columns.

stibnite? ryalgan?

Sugilite - Mohs 6-6.5

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Sugilite is wonderfully purple gemstone from South Africa. Although sugilite does occur elsewhere in the world and in other colors, the manganese in the South African stones give them a range of purple from vivid reddish purple to violet (bluish purple) to dark purple. The manganese can also appear as black spots in the stones and you will sometimes see inclusions of bluish-grey richterite. Most sugilite is opaque, but there are truanslucent specimens. When translucent, it is often referred to as "gel" or "gemmy".