Entries Tagged 'Gemstone Series' ↓

Andalusite is an aluminum silicate mineral (Al2SiO3). Two minerals with the same composition but different structure (polymorphs) as andalusite are kyanite and sillimanite. Andalusite is one of my personal favorite gemstones because it is generally brown in color (there aren’t too many brown gemstones and I love to wear brown!) and it exhibits a property called pleochroism – it appears different colors from different directions. Andalusite can appear orange, green, or brown (all colors that I love to wear!), depending on what direction you view it from.

The transparent variety of andalusite that I use in my jewelry is somewhat uncommon. The opaque variety is more common, and it is often known as cross stone or chiastolite. When viewed down the c-axis, it displays a cross. This stone can be quite striking when cut en cabochon.

Andalusite has a hardness of about 7 1/2 on Moh’s hardness scale, but it is fairly brittle (easy to break). Andalusite is a metamorphic mineral, which occurs in schists, gneisses, and placers. Deposits are found in Australia, Brazil, Canada, Russia, Spain (Andalusia), Sri Lanka, and the US (Schumann, Gemstones of the World).

There is a dark green variety of andalusite called viridine, which contains iron and manganese.

Google image results for andalusite.
Andalusite entries on webmineral and mineral galleries.

Traditionally, blue sapphire is September’s birthstone, but since sapphire can be so many different colors, I say why not break from tradition and choose your favorite color?

Sapphire is a gemstone variety of the mineral corundum. Ruby is the red variety of corundum, and the term “sapphire” applies to any other color of gemstone corundum. Sapphires form in just about every color, including white, pink, orange, yellow, green, blue, purple, and black. Blue sapphire gets its color from trace amounts of the ions Fe2+ and Ti4+. Corundum is an aluminum oxide (Al2O3) mineral , and it forms in aluminum-rich, silica-poor geologic environments such as pegmatites (very coarse-grained granite), and contact zones between limestone and intrusive igneous rocks.

Economically important deposits of sapphire are found in Australia, Burma, Sri Lanka, and Thailand (Schumann, Gemstones of the World). Large sapphires are rare.

Corundum is one of the hardest gemstones, with a hardness of 9 on Moh’s hardness scale (where diamond is a 10). It is also a tough mineral (difficult to break).

Some sapphire exhibits an optical property called asterism. This type of sapphire is called star sapphire. It is sapphire with silk (tiny long mineral inclusions – usually rutile) growing in all directions, so that a 6-rayed star of light appears when viewed from certain angles. Star sapphire is best cut en cabochon. Because star sapphire is not worth as much on the market as traditional faceted sapphire, the gemstones are often heated to remove this beautiful optical effect.

Both heating and dying are common treatments applied to sapphire to increase its beauty and value.

Google image results for sapphire.
Sapphire on webmineral and mineral galleries.

Spinel is a beautiful, and in my opinion, greatly underappreciated gemstone. It forms in a large variety of colors (red, pink, blue, violet, yellow, orange, green, black, brown), and it is a very durable stone. It has a hardness of 8 on Moh’s hardness scale, and it does not fracture easily. Spinel is a magnesium aluminum oxide (MgAl2O4).

Spinel is actually a family of related minerals. Types of gem-quality spinel include flame spinel, balas spinel, pleonaste, hercynite, gahnite, gahnospinel, and picolite (chrome spinel).

Historically, spinel was not known as a separate mineral. It was usually called ruby, and many famous rubies were later found to actually be spinel. The Black Prince’s Ruby in the English Crown and the Timur Ruby in the English Crown Jewels are two such examples.

Spinel is found in placer deposits, along with ruby, in many locations around the world. Important sources include Burma, Cambodia, and Sri Lanka. Like ruby, spinel is a metamorphic mineral found in limestones, dolostones, and low-silica alkali igneous rocks.

Synthetic spinel was first created in 1919. Synthetic spinel has been used as a imitation for many gemstones including diamond, ruby, and sapphire.

Google image results for spinel.
Spinel entries on webmineral and mineral gallery.

Unlike most minerals that are used as gemstones, which are silicate minerals, apatite is a phosphate mineral. It is less durable than a lot of gemstones; it is about a 5 on Moh’s hardness scale, and it fractures somewhat easily.

Apatite derives its name from a Greek word meaning “cheat,” because it is so easily mistaken for other gemstones. Apatite is a transparent mineral that forms in a variety of colors, including colorless, yellow, pink, blue, green, and violet. The apatite commonly used as gemstone is typically an aqua to teal blue, green, or yellow color. The colors of the apatite stones I have purchased tend to be extremely vivid.

Apatite deposits are fairly common worldwide. It can be found as grains in igneous, metamorphic, and sedimentary rocks. The large crystals used as gemstones are found in contact metamorphic rocks.

More information on apatite can be found on webmineral and the mineral galleries site.

Google image results for apatite.

Metaphysical information on apatite.

Prehnite is another gemstone that seems to be surrounded by some confusion. I have seen prehnite referred to as a type of garnet, or as an alternative name for tourmalated/tourmalinated quartz. I have also seen prehnite consistently misspelled as phrenite, pernite, and prenite. Prehnite is not a type of garnet or quartz; it is a calcium aluminum silicate mineral. Prehnite is a phyllosilicate. It is typically yellow-green to brown-yellow in color. (Most of the prehnite I have purchased is a celery green color.) Prehnite ranges from transparent to translucent. Prehnite does not sparkle, but it has a glow that I personally find very soothing to look at. Some prehnite exhibits a cat’s eye effect, and is best cut en cabochon.

Prehnite has a Moh’s hardness of 6-6 1/2 (about the same hardness as quartz, sometimes a bit less). It has a good cleavage, making it easier to break (and therefore less durable) than quartz.

Deposits of prehnite are found in Australia, China, Scotland, South Africa, and the United States (Schumann, Gemstones of the World.) Prehnite is found in hydrothermally altered rocks. It is associated with xeolite minerals (although it is not a xeolite mineral itself.)

More information on prehnite can be found at the mineral galleries site and webmineral.

Google image results for prehnite.

Metaphysical information on prehnite.

I’ve seen vesuvianite mistakenly called vessonite, or referred to as a type of garnet, but it is in fact the mineral idocrase, with no relation to garnet. Vesuvianite is usually an olive green color, but idocrase also occurs in yellow-brown and pale blue. It is a complicated calcium aluminum silicate mineral, with a wide range of compositions and therefore physical properties. It has a Moh’s hardness of 6.5 (which is comparable to quartz), and it is pretty durable.

Deposits of vesuvianite are found in Brazil, Mexico, Kenya, Russia, Switzerland, Sri Lanka, and the United States (Schumann, Gemstones of the World).

Vesuvianite is found in skarns (limestones that have been subjected to contact metamorphism). Vesuvianite got its name from the volcano Vesuvius, where it was first found.

Other varieties of idocrase include cyprine (light blue), Californite (also called California Jade), xanthite, and wiluite.

According to thatcrystalsite.com: “Vesuvianite provides a link to the higher self and the information it offers to the soul in incarnation. Psychologically, it releases feelings of imprisonment and restraint. It is helpful for healing past-life experiences of being a prisoner, of extreme danger, or of mental or emotional restraint; it gently dissolves anger and alleviates fear, creating inner security. Vesuvianite (Idocrase) has powerful mental connections. It opens the mind and clears negative thought patterns so that the mind can function more clearly. It stimulates inventiveness and the urge to discover, linking this into creativity. Vesuvianite can be used to promote loyalty to mankind. It represents cooperative effort and is a wonderful stone to present to newlyweds, business associates, friends and acquaintances. It also assists in the control of the creative and intuitive aspects of the inner realm. Unlocks and stabilizes the mental faculties, helping to clear negative thought patterns from the mental, emotional, an physical bodies and helps one to recognize that which is important to further ones advancement along the spiritual path.”

More information on vesuvianite can be found at webminerals.com and mineral galleries.com.

Google image results for vesuvianite.

If you haven’t seen chrome diopside before, you’re in for a treat.

Chrome diopside is a green variety of the mineral diopside. The chrome diopside I’ve used is a vivid, vibrant green, and it is less blue-ish in color than the emeralds I’ve used. It has such wonderful clarity too.

Diopside is a pyroxene mineral that forms in monoclinic columnar crystals. Another cool property of diopside is that it fluoresces in black light. Diopside is a 5-6 on Moh’s hardness scale (where diamond is a 10), and it can cleave somewhat easily. Because of its relative softness, it is better suited to items like earrings and pendants, rather than rings and bracelets, which tend to get knocked around a bit.

Chrome diopside owes its green color to the presence of chromium. This beautiful green gem is mined in eastern Siberia. It is a somewhat rare gemstone, but since the recent opening of former Soviet countries to the west, it has become more readily available here. Lucky for us, because it is truly a treat!

P.S. If anyone is interested in more technical detail on gemstones, just let me know! I’d be happy to start writing more detailed posts.

Lava Jewelry has many styles featuring pretty green peridot, August’s birthstone. So don’t forget those August birthdays!

Peridot is a lime- to olive-green transparent gemstone that is a silicate mineral called olivine. Olivine is found as crystals in basaltic lava (like the lava in Hawaii and New Mexico).

From mineralminers.com: “Peridot is said to bring healing and vitality to the whole body. It is also said to increase patience, confidence and assertiveness. Peridot is said to help slow the aging process, and to aid in the treatment of digestive, heart, lung and eye disorders. It is also said to be helpful in facilitating the birthing process. ”

I talked a little about ruby last week. Now I’d like to talk about July’s more affordable birthstone: carnelian.

Carnelian is the orange variety of the the gem chalcedony. Chalcedony is a variety of microcrystalline quartz. Carnelian achieves its orange color when it is heat-treated. Carnelian is the first gemstone to have been enhanced by man to improve its appearance. Ancient Egyptians heated carnelian to enhance its color, much the same way we do today. Carnelian ranges in color from a very bright orange to a deep, almost red, orange. Its color caused by the presence of hematite (iron oxide). On Moh’s hardness scale (where diamond is a 10), carnelian is about a 6.5-7.

From jewelrysupplier.com:
To many Carnelian is a powerful motivation stone and some have called it the “Self-Esteem Stone.”

Physical Healing
Because of its connection to the 2nd Chakra, New Age healers believe Carnelian to be instrumental in maintaining health in the lower abdomen. They use it to treat impotence, menstrual cramps, infertility associated with this region. However, they have also turned to its power for healing neuralgia, rheumatism, asthma, skin and blood conditions and insomnia. It is considered so effective in healing dermatological ailments such as acne and psoriasis, that some even recommend Carnelian for the treatment of skin disorders of pets.

Ruby is probably the best known of July’s birthstones. It has traditionally been considered one of the precious gemstones (along with diamond, emerald, and sapphire) – although in recent years, gemologists have turned away from the terms “precious” and “semi-precious” gemstones. (Some stones traditionally considered “semi-precious” – such as a green variety of garnet called tsavorite – can sometimes be worth more than “precious” stones!)

Ruby is the red variety of the mineral corundum. Sapphire is also a variety of corundum, and it includes a huge array of colors, including blue, white, green, and pink. Ruby owes its color to trace amounts of chromium in its crystal structure. Corundum has a hardness of 9 on Moh’s scale, second only to diamond. Because of its hardness, it is commonly used as an abrasive (sandpaper). Corundum is found in a variety of geologic settings – sedimentary, igneous, and metamorphic.

From mineralminers.com: “Ruby: is said to inspire love, and to enhance creativity, wisdom and spirituality. It is also said to give confidence, self-esteem and courage, and to stimulate leadership qualities. Ruby is also said to have been helpful in treating heart and circulatory disease.”