From galleries.com

The gemstone Amethyst is the Birthstone for February. It is also the Zodiac stone for the constellation of Pisces. Amethyst is associated with spirituality, wisdom, sobriety, and security.

Amethyst is the purple variety of the mineral quartz and is a popular gemstone. Although it must always be purple to be amethyst, it can and does have a wide range of purple shades. Its color is unparalleled, and even other, more expensive purple gemstones are often compared to its color and beauty. If it were not for its widespread availability, amethyst would be very expensive.

The name “amethyst” comes from the Greek and means “not drunken.” This was perhaps due to a belief that amethyst would ward off the effects of alcohol, but most likely the Greeks were referring to the almost wine-like color of some stones that they may have encountered.

Amethyst can occur as long prismatic crystals that have a six sided pyramid at either end or can form as druzes that are crystalline crusts that only show the pointed terminations. As a mineral specimen, amethyst is popular for its color and nice crystal shapes that produce a handsome, purple, sparkling cluster.

However, amethyst is not the same everywhere. Different localities can produce a unique amethyst to that particular region or even to that particular mine. Experts can often identify the source mine that a particular amethyst came from. The key to this is the specimen’s color, shape of crystal, inclusions, associations and character of formation.

The following is a list of many of the more noteworthy localities and some of the attributes that characterize the amethyst found there.

• Vera Cruz, Mexico — very pale, clear, prismatic crystals that are sometimes double terminated and have grown on a light colored host rock. Crystals are typically phantomed, having a clear quartz interior and an amethyst exterior. Some are sceptered and phantomed.
• Guerrero, Mexico — dark, deep purple, prismatic crystals that radiate outward from a common attachment point. Often the crystals are phantomed opposite of Vera Cruz amethyst having a purple interior with a clear or white quartz exterior. These are some of the most valuable amethysts in the world.
• Minas Gerais and Rio Grande do Sul, Bahaia, Brazil — crystals form in druzy crusts that line the inside of sometimes large volcanic rock pockets or “vugs”. Some of the vugs may have formed from trees that were engulfed in a lava (or ash) flow millions of years ago and have since withered away. Other vugs are just gas bubbles in the lava. Some vugs can be quite large. The crystals that form are usually light to medium in color and only colored at the tops of the crystals. Most clusters form with gray, white and blue agate and have a green exterior on the vugs. Calcite sometimes is associated and inclusions of cacoxenite are common. On occasion, even excellent crystals of gypsum have been found nestled inside these amethyst lined vugs.
• Maraba, Brazil — large crystals with unattractive surfaces that are of a pale to medium color and often carved or cut into slices. The large “Maraba points” are nearly always polished to remove the rough and milky surface, revealing the beautiful purple amethyst inside.
• Thunder Bay, Canada — a distinct red hematite inclusion just below the surface of the crystals is unique to this locality. Clusters are druzy crusts that line the fissures formed in ancient metamorphic rocks.
• Uruguay — crystals are dark to medium and form in druzy crusts of small crystals that line the inside of volcanic vugs that have a gray or brown exterior. The crystals are usually colored throughout, unlike the Brazilian crystals, and form with a multicolored agate that often contains reds, yellows and oranges. Often amethyst- coated stalactites and other unusual formations occur inside these vugs. The intense color of these druzy crusts is exceptional.
• Africa — crystals are usually large but not attractive. However, the interior color and clarity are excellent and polished slices and carvings as well as many gemstones are prized and admired.
• Maine, USA — Dark druzy clusters that are not widely distributed today.
• North Carolina, USA — Druzy clusters that have a bluish-violet tint.
• Pennsylvania, USA — druzy clusters that filled fractures in metamorphic rocks. They are generally a brownish purple and patchy in color.
• Colorado, USA — druzy clusters form crusts inside of fissures in sandstone, often on top of a crust of green fluorite. Crystals are dark but rather small.
• Italy — both Vera Cruz like crystals, although not as well defined, and large parallel growth clusters with good evenly distributed color.
• Germany — associated with colorful agates that form a druzy light-colored crust.
• Ural Mountains, Russia — a very clear and dark variety that is cut for fine expensive gemstones, natural uncut clusters are rarely on the market.

Often, cut gems of amethyst are graded using the terms: Siberian, Uruguayan or Bahain to represent high medium and low grade respectively, regardless of the actual source. Because of the patchiness of the color distribution in the crystals, Amethyst is often cut as brilliant round cuts to maximize the color. Other cuts can be used when the color is better distributed.

The color purple is traditionally the color of royalty and amethyst has been used since the dawn of history to adorn the rich and powerful monarchs and rulers. Today, amethyst is a lovely and affordable gemstone that is fortunately available in a wide variety of cut and uncut stones that we can all possess and admire.

Prasiolite is the leek-green variety of quartz, rare in nature but used as a gemstone, sometimes (wrongly) called Green Amethyst.

Moonstone/Oligoclase from galleries.com

Chemistry: Na(90-70%) Ca(10-30%) (Al, Si)AlSi2 O8, Sodium calcium aluminum silicate.

Class: Silicates

Subclass: Tectosilicates

Group: Feldspars

Uses: ornamental and semi-precious stone and as mineral specimens.

Specimens

Oligoclase is not a well-known mineral but has been used as a semi-precious stone under the names of sunstone and moonstone. Sunstone has flashes of reddish color caused by inclusions of hematite. Moonstone shows a glowing shimmer similar to labradorescence, but lacking in color. The display is produced from lamellar intergrowths inside the crystal. These intergrowths result from compatible chemistries at high temperatures becoming incompatible at lower temperatures and thus a separating and layering of these two phases. The resulting shimmer effect is caused by a ray of light entering a layer and being refracted back and forth by deeper layers before it exits the crystal. This refracted ray has a different character than when it went in and produces the moonlike glow. Moonstone is an alternate birthstone for the month of June.

Oligoclase is a member of the Plagioclase Feldspar Group. The plagioclase series comprises minerals that range in chemical composition from pure NaAlSi3 O8, Albite to pure CaAl2 Si2 O8 , anorthite. Oligoclase by definition must contain 90-70% sodium to 10-30% calcium in the sodium/calcium position of the crystal structure. The various plagioclase feldspars are identified from each other by gradations in index of refraction and density in the absence of chemical analysis and/or optical measurements.

All plagioclase feldspars show a type of twinning that is named after albite. Albite Law twinning produces stacks of twin layers that are typically only fractions of millimeters to several millimeters thick. These twinned layers can be seen as striation like grooves on the surface of the crystal and unlike true striations these also appear on the cleavage surfaces. The Carlsbad Law twin produces what appears to be two intergrown crystals growing in opposite directions. Two different twin laws, the Manebach and Baveno laws, produce crystals with one prominant mirror plane and penetrant angles or notches into the crystal. Although twinned crystals are common, single crystals showing a perfect twin are rare and are often collected by twin fanciers.

PHYSICAL CHARACTERISTICS:

Color is usually off-white or gray or pale shades of green, yellow or brown.

Luster is vitreous to dull if weathered..

Transparency crystals are translucent to transparent.

Crystal System is triclinic; bar 1

Crystal Habits include blocky, or tabular crystals. Crystals have a nearly rectangular or square cross-section with slightly slanted dome and pinacoid terminations. Twinning is almost universal in all plagioclases. Crystals can be twinned according to the Albite, Carlsbad, Manebach and Baveno laws. Oligoclase can be found as a major rock forming component in granites and syenites.

Cleavage is perfect in one and good in another direction forming nearly right angled prisms.

Fracture is conchoidal.

Hardness is 6 – 6.5.

Specific Gravity is approximately 2.64 – 2.68 (average)

Streak is white.

Associated Minerals are quartz, muscovite and K-feldspars.

Other Characteristics: index of refraction is 1.533 – 1.552. Lamellar twinning may cause a grooved effect on cystal and cleavage surfaces that appear as striations.

Notable Occurrences include Sri Lanka; New York, USA; Russia; Sweden and Canada.

Best Field Indicators are occurrence, twinning striations, shimmer, density and index of refraction.

All About Rainbow Moonstone & It’s Hidden Powers from lakaiser.com

Rainbow moonstone.. such a magical stone! The name ‘Rainbow Moonstone’ was given due to the gemstone’s white sheen color that changes if it is rolled or rotated. The iridescent flashes on the gemstone have captivated the hearts of jewelry lovers for centuries. Moonstone is a mineral of the feldspar group and the optical phenomenon that causes the color play is known as Adularescence. The light moves across the gem much like the moonlight glides over a large body of water hence causing the extraordinary glow. The light reflects off of the thin layers of the feldspar minerals within the moonstone. The layers act as a diffuser, hence softening the light and allowing it to bounce around.

With its otherworldly facade, moonstone has mesmerized people of different cultures. Its use can be traced back to the ancient civilizations. The Romans believed that the moonstone was born from the solidified rays of the moon. The Greeks and the Romans have long associated the gem with their lunar gods. Other cultures strongly coveted that the stone’s powers were with the moon. It was especially prized during a full moon.

Although the Rainbow Moonstone found its way into jewelry throughout history, it wasn’t until the early 1900s that the stone became an iconic focal point. Rainbow Moonstone became immensely popular with various artists and goldsmiths during the Art Nouveau period, in the early 20th century. In the preceding years it was mainly used as an accent stone. Artisans like René Lalique focused on using natural, mystical stones with unique properties which were favored over glitzy stones. But the movement was short lived and it was soon followed by Art Deco which emphasized on the use of diamonds and precious gemstones. It wasn’t until the late 1960s that moonstone came back into fashion.

Seen as a veiled spectacle of light passing over the moon, the gemstone is highly valued among the monks, shamans, spiritualists, and devotees from various religions. The pearly iridescence it showcases holds a deep meaning and has a towering significance.

As ancient as the moon itself, the meaning of the Rainbow Moonstone lies within its playful glimmer. Its power nourishes, gives passion and awakens your feminine energies. The gemstone has the ability to not only heal you but is believed to guide you to your inner path. With the waxing and waning of the moon, it evokes tranquility and peace that has a sensual, enigmatic feel to it. It emanates an exuberance that can re-energizes a person’s mind, body and wash the negativity away. Enveloped in gleaming rays of gold, blue and purple the Rainbow Moonstone is embraced with white energy that makes it a protective gem.

But what does it really mean?

Often connected to the water signs, the Rainbow Moonstone is associated with lots of healing properties :

Enhances intuition

Makes wearer more accepting of change

Alleviates fear associated with change

Balances emotions

Promotes a calm mood

Encourages peace, harmony, and balance

Improves confidence

Helps a person become more passionate

Often called the “visionary stone”, Rainbow Moonstone mostly occurs in the regions of Armenia, Australia, the Alps in Austria, Mexico, Madagascar, Myanmar, Norway, Poland, India, Sri Lanka and the United States.

From mycrystalaura.com.au

Crystals:

Citrine

Agates

 Aventurine

 Mica

Pumice