Desert Messenger

14 www.DesertMessenger.com December 3, 2014 SEE ROCKS PAGE 24 ADVENTURES WITH ROCKS One of my absolute favorite stones is agate. They come in just about all patterns and colors. A close second is jasper. Those, too, are found in all patterns and colors. But what exactly is an agate? And what is the differ- ence between an agate and a jasper? Both agates and jaspers are varieties of quartz known as chalcedony (pro- nounced Cal-Sidney). Silica Dioxide (SiO2), also known as quartz, is one of the most common minerals in the earth's crust. There are two major types of quartz: macrocrystalline, meaning "large crystal", and crypto- crystalline, meaning the crystals are By Jenn Jedidiah Free for RocksInMyHead™ Agates - to be or not to be...that is the question too small to be seen with the naked eye. Examples of macrocrystalline quartz are clear quartz, smoky quartz, citrine, amethyst and others. Chalcedony and its varieties are crypto- or micro- crys- talline forms of quartz. Technically, the term Chalcedony includes any type of cryptocrystalline quartz, however in the gemstone world it is only used to describe whitish or light blue translu- cent material. Chalcedony has a hard- ness of 7 on the Mohs scale. Both agates and jaspers are varieties of chalcedony in the technical sense- they are cryptocrystalline forms of quartz. This brings us to our original question: If they are both chalcedony, then what is the difference between them? This is a good question, because in some cases the difference is well defi ned, but in others it is not. Technically, the pri- mary difference between an agate and a jasper is diaphaneity – a word used to describe "how easily light passes through a material". There are three specifi c levels of diaphaneity: trans- parent, translucent, and opaque. Mi- crocrystalline quartz in its pure form is semitransparent. When impurities or foreign materials are added from the surrounding rocks and minerals, the color of the microcrystalline quartz changes and the ability of light to pass through it decreases. Agate is a translucent to semitranspar- ent chalcedony, which means light will pass through it. Agates typically have variegated, wavy, or irregular bands, but sometimes the bands are not visible, or instead of bands, the stone has dendrit- ic, plume, or mossy inclusions. Agates form in areas of volcanic activity where water rich in dissolved silica (SiO2) fl ows through cavities and fractures in igneous rock such as basalt and rhyolite. The silica-rich solution leaves layers of silica gel on the walls of these cavities, which slowly crystallize and build up. As the mineral composition of the silica (other minerals, or impurities, carried with the SiO2 in the water) changes over time, the color of the microcrystalline quartz is altered, forming different col- ored layers (bands) or inclusions. Jasper, on the other hand, is an opaque variety of chalcedony. Jasper contains enough impurities (other minerals be- sides silica) to make it opaque. So the real difference between jasper and ag- ate is the amount of impurities that are in the specimen. Also, rather than in cavities in igneous rock, jasper typi- cally forms in soft sediments when fi ne particulate materials are deposited and cemented into a solid mass by the sil- ica. The colors and patterns of jasper are determined by the mineral particu- lates in that mass. But agates and jaspers will not always conform themselves to our classifi ca- tions. In many instances, jaspers have translucent zones, or areas where ag- ate has developed. Some agates can be mostly opaque with a few bands of translucency. While these "jaspa- gates" may confuse our defi nitions of them, they can also be some of the most beautiful and interesting specimens. Besides, they formed millions of years before we ever came along to assign the rules, anyway. VFW Post 769 VETERANS OF FOREIGN WARS 120 S. Palo Verde, Quartzsite, AZ, 928-927-7697 The Canteen is a smoking establishment • Members & Guests Only for Alcohol Service ACTIVITIES FOR CORPORAL BEN SCOTT POST 769 AND LADIES AUXILIARY 769 We are collecting coupons you may have that you won't use. These go to the military families who can use them up to 6 months after expiration. Collection boxes will be placed in businesses around Town, churches, and at the Post. Please help us in this endeavor to assist our Veterans. CALENDAR OF EVENTS: December 6 – Rose and Gary Fraser Me- morial ChickNik at Fire Station – 12 to 4p.m. which is a benefi t to assist those training for fi re fi ghting. December 6 – Christmas Light Parade at dark. Come out and enjoy the fl oats December 7 – Pearl Harbor Day Flag Cer- emony – 10:48 a.m. Also Pot Luck (entrée provided) – 12:00 noon. December 10 - Party to Honor/Remember Fallen Veterans at Post noon-4pm December 13 - Christmas Wreath Parade to Cemetery. Wreath laid at monument to remember our veterans at Christmas time. Everyone is encouraged to attend. Starts at 3pm at Post December 20 – Christmas Party and Pot Luck – 2:00 p.m. Annual Borderline Riders Christmas Run in Yuma. Funds raised are used to assist homeless Veterans. December 25 - Merry Christmas! Chirstmas Party at Post 10am-4pm January 10 – Hi-Jolly Parade sponsored by VFW. More information coming soon. Check our VFW Post 769 website for additional activities www.vfwpost769.org Comrades meeting -Dec. 13 - 9:00 a.m. at Post Ladies Auxiliary meets- Dec. 13 - 9 a.m. at Post House Committee meets - Dec. 13 - 10 a.m. at Post Mens Auxiliary – Dec. 8 - 1 p.m. at Post District 1 Riders meeting 2nd Sat 2 p.m. - TBA Corner of Moon Mt. & Cowell • Quartzsite • 928-927-5400 QUARTZSITE'S ONLY YEAR ROUND SALON Sandy, Debbi, Cheyanne, Beth, Linda, Jo, Sheryl & Janna ARE BACK WELCOME BACK SNOWBIRDS! FOR ALL YOUR Hair, Massage, Manicure and Pedicure Services DEADLINE : WED. DEC, 10 TH for DEC 17 th edition Desert Messenger Email: editor@DesertMessenger.com 928-916-4235 www.DesertMessenger.com

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