Topic: Mineralogy

Azjah · Date: 2008-03-09 21:21 EST

The Museum of Natural History in RhyDin had been small, and from all appearances to Azjah?s mind, woefully neglected. She?s spoken to the Curator, and had promised to return with a mineral exhibit that she would put on long term loan to the Museum.

Some of her collection was simply too rare to donate permanently, but if they went to the Museum, more people could see them, and they would serve a wider purpose.

She?d already decided to donate the large sapphire from the mining project, and thankfully it wasn?t one that Kairee had any interest in. The sapphire was the largest, purest example ever found. It would form a fine centerpiece for the display she had in mind.

Dyson listened to her instructions and made a few mental notes before leaving to find the specimens. Most of them would be in the library, but the most valuable ones he would need to open the safe.

In the morning, Azjah found the specimen?s laid out neatly along with a data sheet for each one neatly formatted on Drachen Walde stationary.

Azjah · Date: 2008-03-09 21:33 EST

1) Sapphire : Blue variety of the mineral corundum. The blue coloring comes from the impurity of titanium. The name sapphire is probably derived through the Latin sapphires and Greek s?pheiros.
. a. Gem quality corundum originates from metamorphic basic rocks that contain aluminum rich minerals, and in some aluminum rich igneous rocks. Associated with sapphire are minerals such as spinel, periclase, tourmaline, kyanite, magnetite, chlorite and nephelinite.
. b. The crystal system is trigonal, and has a Moh?s Hardness of 9. These are the hardest gems with only diamond exhibiting a Moh?s Hardness of 10. Density averages 4.0 grams/cubic centimeter of mineral.
. c. Sapphires of this purity are extremely rare, and the deep blue coloring in a stone weighing 42 carats has never been documented previously.
. d.The distinctive characteristics are sapphires include striking luster, blue-green pleochroism, and in the case of star sapphires, needles of rutile.
. i..(Pleochroism is the breaking up of light into two parts. Each of the rays travels at a different velocity resulting in doubly refracted light)

http://i272.photobucket.com/albums/jj171/Azjahh/sapphire.jpg

http://i272.photobucket.com/albums/jj171/Azjahh/250px-Sapphire01.jpg

Azjah · Date: 2008-03-09 21:41 EST

2) Ruby: Red variety of the mineral corundum. This is the most highly prized gem of the corundum series. The name Ruby comes from the Latin Rubrum for red. The red color is caused by the presence of Chromium.
. a. Color varies from pale pink shades to vibrant violet red. This gem is pleochroic, and different colors are found in the same sample.
. b. The crystal system is trigonal, and has a Moh?s Hardness of 9. These are the hardest gems with only diamond exhibiting a Moh?s Hardness of 10. Density averages 4.0 grams/cubic centimeter of mineral.
. c. Rubies in excess of 3 carats at this purity are exceedingly rare and can command prices in excess of diamonds for similar purity and size.

http://i272.photobucket.com/albums/jj171/Azjahh/150px-Ruby_cristal.jpg

Azjah · Date: 2008-03-09 21:47 EST

3) Chrysoberyl: Also know as golden chrysoberyl, a synonym, the prefix ?chryso? being Greek for ?golden?. This sample is the common form of twinned crystal structure.
a. The color can vary from yellow to greenish-yellow.
b. The mineral is orthorhombic which lends itself to easy twinning.
c. It is derived from beryllium aluminates, having a Moh?s hardness of 8.5. Specific gravity between 3.5 ? 3.8. Generally found in granite pegmatites and metamorphic gneisses.
d. Pleochroic in the green and brown varieties.

http://i272.photobucket.com/albums/jj171/Azjahh/180px-Chrysoberyl_yellow.jpg

http://i272.photobucket.com/albums/jj171/Azjahh/180px-Alexandrite_26_75cts.jpg

Alexandrite - Beryl gem

Azjah · Date: 2008-03-09 21:53 EST

4) Topaz: This is a silicate of aluminum containing fluorine and hydroxyl. The name Topaz was originally applied to an olivine mineral taken from the Island of Topazos, but came into use for the mineral we call Topaz today in the first half of the 18th century.
a. Crystal system is orthorhombic, and crystals are often found in prismatic form, sometimes with the terminal faces intact. They have perfect basal cleavage.
b. Colors range from white, semi-opaque to colorless, honey-brown, to rare pinks and reds.
c. Topaz has a hardness of 8 and density of 3.52 ? 3.56 grams per cubic centimeter.
d. Topazes richest in hydroxyl have a low density and high refractive indices.
e. Topaz is characteristic of pegmatites and pneumatolytic deposits. Therefore contact metamorphic zones are where the minerals are economically mined.
. i. (Cleavage: atomic structure of each mineral is unique, but fall into defined categories dependent on fixed angular relationships between atoms. Topaz has orthorhombic structure, which results in a relatively smooth and lustrous face when fractured.)
. ii. (Pegmatite: Generally associated with granites and syenites. The size of the grains and crystals are gigantic in relation to most rock formations. They are the premier source of economic mineral deposits.)
f. Yellow topaz is the most common form of Topaz used in jewelry. However, the easy basal cleavage makes this gem rather brittle.
g. Blue topaz has become the most prevalent form of Topaz sold today. The value of topaz is very low, which makes it readily available and sold for its brilliant blue shades in place of blue sapphire.

http://i272.photobucket.com/albums/jj171/Azjahh/170px-TopazUSGOV.jpg

http://i272.photobucket.com/albums/jj171/Azjahh/160px-Topaz_red.jpg

http://i272.photobucket.com/albums/jj171/Azjahh/160px-Topaz_cut.jpg

Azjah · Date: 2008-03-09 22:01 EST

5) Beryl: Emerald is the gem version of Beryl. Beryl is a silicate of beryllium and aluminum, with the green coming from impurities of Chromium and Vanadium.
. a. Chrystal system is hexagonal.
. b. Hardness ranges between 7.5-8 but is fairly brittle and has ill-defined cleavage along the basal plane.
. c. Density: 2.67 ? 2.72 grams per centimeter. Refractive index, like density varies depending on aluminum content.
. d. Beryl is an accessory mineral in granitic pegmatites, where crystals have been discovered reaching 40 centimeters in length.
. e. The name ?emerald? is very ancient in origin. The Latin smaragdus appears to have referred to emeralds for the last 2200 years.
. f. The brilliant green is the most prized version of Beryl. The color is due to inclusions of Chromium atoms into the Beryl matrix.
. g. Stones of greater than 2 carats and good transparency are highly valued.

http://i272.photobucket.com/albums/jj171/Azjahh/225px-C389meraude_28BrC3A9sil29.jpg

Emerald with host rock

http://i272.photobucket.com/albums/jj171/Azjahh/250px-Gachalaemerald.jpg

Largest emerald ever found. 858 carats

Azjah · Date: 2008-03-29 19:58 EST

6) Grossular garnet: A silicate of calcium and aluminum and part of the garnet group of minerals. The name grossular comes from the Latin for gooseberries because in this form, the crystals do appear as clusters of this fruit.
a. Crystal system: cubic, usually manifested as a rhombic dodecahedron
b. Varies from transparent to semi-opaque, and shades from light yellow green to pinkish hues.
c. Hardness: 6.5 ? 7.5, density 3.58 ? 3.69 grams per cubic centimeter.
d. Grossular garnet is not a rare mineral, and is not used in gem work. But is highly prized by collectors for the beauty of the resulting crystal structures.

http://i272.photobucket.com/albums/jj171/Azjahh/GRO-30GrossularGarnetGreen.jpg

http://i272.photobucket.com/albums/jj171/Azjahh/GRO-28cGrossularGarnethoney.jpg

http://i272.photobucket.com/albums/jj171/Azjahh/GRO-27grossulargarnetred.jpg

Azjah · Date: 2008-03-29 20:19 EST

7) Tourmaline: A complex borosilicate of aluminum and alkali with iron and magnesium cations. The name is apparently derived from the Sinhalese turamali referring to gems of unknown origin.
a. Chrystal system: trigonal
b. Appearance: long, three sided prisms consisting of one of the widest color variants of any naturally occurring mineral. The most common color is black, but may be anything from pink to violet red, brownish green, light or dark blue to totally colorless. The prized ?Watermelon? variant has a pinkish interior and transitions to a greenish outer.
c. Hardness: Moh?s scale 7, density of approximately 3.02 ? 3.20 grams per cubic centimeter. The darker variants have the higher densities.
d. Refractive indices exhibit quite marked birefringence and strong pleochroism.
e. Tourmaline is found in differentiated dykes of granitic pegmatite.

The four most common, and well known tourmalines are distinguished by their color and transparencies. Elbaite is the gemstone tourmaline and comes in many varied and beautiful colors. It is transparent to translucent and is highly prized as minerals specimens and as gemstones. Elbaite is easily the most colorful of all the gemstones.

The iron rich schorl is the most abundant tourmaline and is black and opaque. It is a common accessory mineral in igneous and metamorphic rocks and can form nice crystals. Although too opaque to be used as a gemstone, schorl is used as an ornamental stone when found as inclusions in quartz, a stone is called "tourmalinated quartz".

The two other more common tourmalines; dravite and uvite are much less common than elbaite or schorl, but they are getting noticed for their beautiful specimens. Some of dravite's crystals are nicely formed, translucent brown and they can reach a rather large size. Uvite is a green translucent to opaque tourmaline that is growing in popularity and is being cut as a gemstone.

The Tourmaline Group has a general formula of AX3Y6(BO3)3 Si6O18(O, OH, F)4. The A can be either calcium or sodium. The X can be either aluminum, iron, lithium or magnesium. The Y is usually aluminum, but can also be chromium or iron. Some potassium can be in the A position, some manganese can be in the X position and some vanadium can be found in the Y position, but these elements are usually not represented in the formulas of the tourmaline members.

http://i272.photobucket.com/albums/jj171/Azjahh/twmm140watermelontourmaline.jpg

Watermelon Tourmaline

http://i272.photobucket.com/albums/jj171/Azjahh/schorltourmaline.jpg

Schorl Tourmaline

http://i272.photobucket.com/albums/jj171/Azjahh/twmm128watermelontourmaline2.jpg

Watermelon

http://i272.photobucket.com/albums/jj171/Azjahh/dra-4cdravitetourmaline.jpg

Dravite

http://i272.photobucket.com/albums/jj171/Azjahh/elb-33Elbaitetourmaline.jpg

Elbaite Tourmaline

Azjah · Date: 2008-03-29 20:43 EST

8) Quartz: The most common mineral known. Silicon dioxide. The name may be derived from querkluftertz, an old German word referring to whitish vein quartz. This common mineral is found in a variety of colors, but often it is the clear clusters of quartz prisms that secure the highest profits.
a. Crystal system: trigonal, resulting in hexagonal, prismatic crystals with pyramidal or bi-pyramidal terminations. These crystals have no cleavage.
b. Quartz comes in a variety of colors from clear and transparent to white and opaque. It may take the pure crystalline form that attracts many collectors to the massive vein forms of quarts. When it takes a microcrystalline form, quartz is called chalcedony and is then called agate, sard, cornelian, etc.
c. Quartz hardness: 7, density 2.65 grams per cubic centimeter and refractive indices of 1.544 and 1.553. These are very constant due to the chemical composition of Quartz.
d. Genesis: The largest crystals originate from the fluids associated with intrusive magmatic phenomena and are found in pegmatitic, pneumatolytic and hytrothermal deposits.
e. Gem variants include Amethyst, derived from the Greek am?thystos, meaning ?not drunken? because it was believed to protect people from intoxication. Amethyst is the most valued gem variant of Quartz.

Major varieties of quartz:

Chalcedony Any cryptocrystalline quartz, although generally only used for white or lightly colored material. Otherwise more specific names are used.
Agate Multi-colored, banded chalcedony, semi-translucent to translucent
Onyx Agate where the bands are straight, parallel and consistent in size.
Jasper Opaque chalcedony, typically red to brown
Aventurine Translucent chalcedony with small inclusions (usually mica) that shimmer.
Tiger's eye Fibrous gold to red-brown coloured quartz, exhibiting chatoyancy.
Rock crystal Clear, colorless
Amethyst Purple, transparent
Citrine Yellow to reddish orange to brown, greenish yellow
Prasiolite Mint green, transparent
Rose quartz Pink, translucent, may display diasterism
Rutilated quartz Contains acicular (needles) inclusions of rutile
Milk quartz White, translucent to opaque, may display diasterism
Smoky quartz Brown to grey, opaque
Morion Dark-brown, opaque
Carnelian Reddish orange chalcedony, translucent

http://i272.photobucket.com/albums/jj171/Azjahh/USDA_Mineral_Quartz_Crystal_93c3951.jpg

http://i272.photobucket.com/albums/jj171/Azjahh/QuartzUSGOVmikly.jpg

http://i272.photobucket.com/albums/jj171/Azjahh/800px-IMG_5779rosequartz.jpg

Azjah · Date: 2008-03-29 20:52 EST

9) Jadeite jade: A variety of jadeite pyroxene used as a gem or ornamental material consisting of microcrystalline aggregates which together with similar aggregates of tremolite-actinolite amphibole come under the general name of jade.
a. Distinctive features: almost alabastine translucence, degree of hardness, and graduated streak.
b. Value: variable as the Imperial translucent jade commands very high prices while paler, more opaque jades are very common and command no greater prices than other stone ware.
c. Jade is a silicate of sodium and aluminum, and is a member of the alkaline pyroxene group of minerals.
d. Crystal system: Monoclinic, occurring as a granular aggregate of small crystals.
e. Hardness of 6.5 ? 7 with extraordinary tenacity. (opposite of brittle)
f. Density: 3.3-3.36 grams per cubic centimeter. Darker shades of green can go as high as 3.4 g/cm2
g. Genesis: Formed by regional metamorphism and in lenticular masses or veins.

Jade, unworked (photos taken from Wikipedia)

http://i272.photobucket.com/albums/jj171/Azjahh/Jadestein.jpg

http://i272.photobucket.com/albums/jj171/Azjahh/600px-Jadeite_Sodium_aluminum_silic.jpg

Azjah · Date: 2008-03-29 20:57 EST

10) Hematite: Iron oxide, one of the common ores of iron mined in many countries. The name comes from the Greek root aima or ema, meaning ?blood? because of the red color of the powdered hematite.
a. Crystal system: trigonal
b. Appearance: occurs as thin, relatively brittle laemellar crystals, polyhedral crystals or lenticular habit. All of them are dark grey to black. They will have a strong metallic luster.
c. Hardness of 6.5 and a density of 5.2 ? 5.3 grams per cubic centimeter. Their refractive index is very high, 2.94 and 3.22. They are extremely difficult to measure, and are not generally used for identification purposes.
d. Occurrence: globally
e. Distinctive features: metallic luster and color, will leave a red streak if drawn across a piece of unglazed porcelain.
f. Uses: beads, necklace pendants, iron ore.

http://i272.photobucket.com/albums/jj171/Azjahh/HematiteUSGOV.jpg

http://i272.photobucket.com/albums/jj171/Azjahh/800px-Rainbow_hematite_MG.jpg

(Photos taken from Wikipedia)

Azjah · Date: 2008-03-29 21:04 EST

11) Rhodochrosite: Manganese carbonate is a member of the calcite series. It?s name is derived from the Greek rh?don, meaning pink.
a. Crystal system: Trigonal, occurs as semitransparent, rhombohedral crystals with poor luster, or as concretionary masses, sometimes with irregular, contorted veining. Normally it is a delicate shade of pink, but can be slightly orange. It has perfect rhombohedral cleavage.
b. Hardness: very low, normally around 4. Density 3.4 ? 3.7 grams per cubic centimeter.
c. Primary economic uses are for ornamental purposes such as beads, small jars and containers

http://i272.photobucket.com/albums/jj171/Azjahh/Rhodochrosite.jpg

http://i272.photobucket.com/albums/jj171/Azjahh/800px-Rhodochrosite_Pink_Form.jpg

Azjah · Date: 2008-03-29 21:13 EST

12) Fluorite: Common mineral with uncommon range of colors due to the presence of impurities and structural defects. It forms large, rectangular crystals, which can fluoresce under ultraviolet light.
a. Hardness: 4 Mohs, specific gravity 3.18
b. Crystal system: Isometric, simple cubes, some octahedrons, with occasional twins.

http://i272.photobucket.com/albums/jj171/Azjahh/Fluorite_crystals_270x444.jpg

http://i272.photobucket.com/albums/jj171/Azjahh/682px-Fluorite_with_Iron_Pyrite.jpg

http://i272.photobucket.com/albums/jj171/Azjahh/800px-Fluorite_Macro_1.jpg

(Photos taken from Wikipedia)

Azjah · Date: 2008-05-12 12:41 EST

13) Wulfenite: Almost a gaudy yellow orange in color, well defined crystals as this almost never forms massive or formless variants. This is from the lead molybdate family. It is a secondary mineral derived from the chemical alteration of ore deposits containing Galena and Molybdenite.
a. Hardness: 2.5 ? 3 Mohs
b. Specific gravity: 6.5 ? 7 grams per cubic centimeter
c. Color: yellow, red-orange to brown
d. Crystals: Tetragonal in thick to thin tablets, usually square in cross section.

Azjah · Date: 2008-05-12 12:43 EST

14) Gold: one of the most sought after metals known to mankind. Nearly impervious to chemical assault. This sample is donated by the artist, Ariel Daratrazanov.
a. Hardness: 3 Mohs
b. Specific gravity 19.3 grams per cubic centimeter
c. Crystal structure: Isometric, octahedral and dentritic.

Azjah · Date: 2008-05-12 12:43 EST

15) Copper: Copper tends to be found in conjunction with silver. It forms beautiful dentritic branches with smaller crystals of cuprite or aragonite.
a. Hardness: 2.5 ? 3 Mohs
b. Specific gravity: 8.95 grams per cubic centimeter
c. Color: Pale red to brown
d. Crystal system: Isometric, dodecahedrons, dentrites

Azjah surveyed the assembled samples. They would compliment the Museum?s small collection of rock samples for the moment. Their collection held the usual examples of pyrite crystals and dollars, next to gold examples to demonstrate the difference between fool?s gold and the real metal. The barite roses, and bladed samples of barite are common, but beautiful. She would work on expanding the exhibit as she could. The

She left message for Dyson that he could have the samples delivered to the Museum of Natural History.