Friday, June 22, 2012

Do you love color? Have a look at the incredible colors of rhodochrosite, haüyne, sphene, yogo sapphires, tanzanites, hiddenite, garnets and benitoites at the Los Angeles County Natural History Museum, in the Butterfly Broach Collection

Butterfly Brooch Collection

This text is from the museum's webpage, and none of the photos was taken by me.

The butterfly brooch collection is on temporary display in the Gem and Mineral Hall for a year, starting May 1, 2012. The collection was created and is owned by Buzz and Bernardine, who have a passion for rare gemstones that they have chosen to share through unique jewelry pieces. The butterfly brooches only represent a third of their entire jewelry collection. Buzz faceted most of the main gems and Bernardine designed all except for the "Ninja" butterfly, which is Buzz's creation. All the metalwork is done in 18kt gold.

Benitoite Butterfly

This brooch is almost entirely set with benitoite, the California state gemstone. A barium-titanium silicate mineral (BaTiSi3O9), benitoite is a rare mineral, crystals large enough to be cut into gemstones are found only in one location: the Dallas gem mine in San Benito County, California. An unusual geologic setting of hydrothermal veins between glaucophane schist and serpentinite created this rare mineral. Benitoite is known for its high dispersion and its vivid blue fluorescence in UV light. While the blue and colorless benitoites are natural, the orange benitoites in the eyes are produced by heat treatment of colorless stones.

Hiddenite Butterfly

A 10.01-ct green hiddenite is the central piece of the brooch. Hiddenite is a green variety of the mineral spodumene (LiAl(SiO3)2) in which the color is caused by small amounts of the element. chromium. Hiddenite from North Carolina is found associated with emerald, the green variety of bery, which also owes its color to chromium. The body of this butterfly is the world's largest faceted hiddenite. It comes from a deposit in North Carolina that is the only important source of hiddenite. The butterfly also contains rainbow feldspar (displaying adularescence) from Madagascar, colorless diamond, and green tourmaline. The eyes are red beryl, the rarest of all varietes of the mineral beryl. Red beryl of gem-quality is found only in the Wah Wah mountains of Utah.

Ninja Butterfly

The featured stone of the "Ninja" butterfly brooch is alexandrite (body and eyes). Alexandrite is a variety of the mineral chrysoberyl (BeAl2O4) that displays a particular feature known as “color change”. The picture of the Ninja butterfly on the left has been taken under incandescent light, and on the right under fluorescent light. Tanzanian purple scapolites and Madagascar blue apatites are set around a 3.58ct Russian alexandrite. While these gems do not change color, they do match the color of the alexandrite uder each type of illumination.  

Opal Butterfly

This butterfly brooch displays a variety of precious opals from Virgin Valley, Nevada. This deposit was a forested valley buried by volcanic ash approximately 15 million years ago. The buried wood was gradually replaced by opal. The most valuable opals are black with a strong play-of-colors. Nearly all Virgin Valley opal has very high water content, so that as soon as it is removed from the ground it starts to dehydrate, causing it to crack (or “craze”). The stones in this butterfly are remarkably free of cracking and represent the tiny minority of stable opals from this locality.

Pearl Butterfly

These natural pearls from the Gulf of California are known as “Baja pearls.” They have been popular since Spanish conquistadors brought them back to Europe. “La Peregrina,” the famous pearl owned by Queen Mary I of England and more recently by actress Elizabeth Taylor, is a Baja pearl. Madagascar rainbow feldspar, colorless diamond and Colombian emerald are also set in this brooch.

Peridot Butterfly

This elegant butterfly brooch is set with green peridot from Pakistan, colorless diamond and orange spessartine garnet from California. Peridot is a nickname for gem-quality forsterite. This mineral is one of the most common in the Earth, but most is located deep underground, in the Earth’s mantle.

Rhodochrosite Butterfly

This butterfly brooch is made entirely of gems from Mexico, including a 13.51ct rhodocrosite (MnCO3). This mineral is very easily scratched, so it is very rare to find it in jewelry; however, its beautiful vivid pink-red color makes it worth some extra care! Apatite and opal cover the wings. The eyes are green chromium-rich titanite (sphene).

Spessartine Butterfly

Orange spessartine garnets from the Little Three mine in Ramona, California highlight this brooch, along with colorless diamonds and green tsavorite garnets from Kenya. The name "garnet" refers to a group of silicate minerals with the same internal arrangements of atoms, but different chemical compositions. Spessartine (Mn3Al2(SiO4)3) is a manganese-aluminum-garnet popular in jewelry due to its bright shades of yellow, orange or red. Tsavorite is a green variety of grossular ((Ca3Al2(SiO4)3), a calcium-aluminum garnet, with impurities of vanadium and chromium, which give the green color.

Spessartine and Benitoite Butterfly

This butterfly features gemstones from California: orange spessartine garnet from San Diego County and blue benitoite from San Benito County.

Spinel Butterfly

Pink and red spinels from Vietnam are the highlights of this butterfly brooch. Red spinel (MgAl2O4) has long been used as an affordable alternative to ruby, which it closely resembles. Some famous historical rubies are actually red spinels. Spinel is now very popular in its own right. The eyes of the butterfly are blue jeremejevites (Al6(BO3)5(F,OH)3) from Namibia. Although beautiful in faceted gems, jeremejevite is seldom used in jewelry because of its great rarity.

Stibiotantalite Butterfly

The butterfly brooch is set with three exceedingly rare kinds of gemstone. The body is a 5.07-carat yellow stibiotantalite from Afghanistan. Stibiotantalite, SbTaO4, gets its name from its chemical composition. It is an oxide of antimony and tantalum, “stibium” being the Latin name for the element antimony. The butterfly wings are set with electric-blue haüyne (sodalite group mineral (Na, Ca)4-8 (Al6Si6(O,S)24)(SO4, Cl)1-2) found in small gas cavities in a volcanic rock in Germany, and the eyes are white cassiterite (SnO2), a tin ore from China.

Green Titanite Butterfly

The multi-colored sparkle of this butterfly emanates from its green titanites (a.k.a. “sphene”) from Madagascar. The "fire" of titanite derives from its very high dispersionand combined high index of refraction. Titanite (CaTiSiO5) is a fairly common accessory mineral in igneous and metamorphic rocks, but is very seldom found in size and quality suitable for gems.

Brown Titanite Butterfly

This butterfly brooch brings together spectacular titanites in three different colors: green from Madagascar, brown from Pakistan, and yellow also from Pakistan.

Tanzanite Butterfly

Natural unheated tanzanite of many different colors can be seen in this butterfly brooch. Tanzanite is a nickname for gem quality varieties of the mineral zoisite from northern Tanzania. Most stones are vivid blue to purple. Stones that are not heat-treated can display very strong pleochroism.

Topaz Butterfly

This butterfly brooch is set with red and pink topaz from Russia, Pakistan and Brazil, along with rainbow feldspars from Magadascar, colorless diamonds and colorless jeremijevites for the eyes. Although most people think topaz is only a yellow gem, in nature most topaz is colorless to pale blue. Topaz gems in shades of deep pink to red are the most prized.

Yogo Sapphire Butterfly

This butterfly brooch is set with blue sapphires from Yogo Gulch, Montana. Sapphire senso stricto is the blue variety of corundum (Al2O3), while the red variety is referred to as ruby. Corundum can come in a variety of colors, and will be then referred as "colored sapphire", such as "pink sapphire", or "yellow sapphire" for example. The blue color is known to be due to charge transfer between titanium (Ti4+) and iron (Fe2+). Yogo sapphires are among the world’s finest sapphires. They are found in a hard igneous rock and because of that, tend to be small crystals and rather difficult to mine. The sapphires are accented by rainbow feldspars from Madagascar and colorless diamonds.