Agate is a rock consisting of cryptocrystalline silica, chiefly chalcedony, alternating with microgranular quartz. It is characterized by its fineness of variety of color. Although agates may be found in various kinds of host rock, they are classically associated with volcanic rocks and can be common in certain metamorphic rocks; the stone was given its name by Theophrastus, a Greek philosopher and naturalist, who discovered the stone along the shore line of the river Achates in Sicily, sometime between the 4th and 3rd centuries BC. Colorful agates and other chalcedonies were obtained over 3,000 years ago from the Achates River, now called Dirillo. Agate is one of the most common materials used in the art of hardstone carving, has been recovered at a number of ancient sites, indicating its widespread use in the ancient world. Agate minerals have the tendency to form on preexisting rocks, creating difficulties in determining their time of formation, their host rocks have been dated to have formed as early as the Archean Eon.

Agates are most found as nodules within the cavities of volcanic rocks. These cavities are formed from the gases trapped within the liquid volcanic material forming vesicles. Cavities are filled with silica-rich fluids from the volcanic material form agate, layers are deposited on the walls of the cavity working their way inwards; the first layer deposited on the cavity walls is known as the priming layer. Variations in the character of the solution or in the conditions of deposition may cause a corresponding variation in the successive layers; these variations in layers result in bands of chalcedony alternate with layers of crystalline quartz forming banded agate. Hollow agates can form due to the deposition of liquid-rich silica not penetrating deep enough to fill the cavity completely. From the reduced cavity within the agate will form crystals, the apex of each crystal will angle towards the center of the cavity; the priming layer are dark green in coloration but can be reduced by iron oxide emitting a rust like appearance.

Agate is a durable mineral and therefore is seen detached from its eroding matrix, once removed, the outer surface is pitted and rough from filling the cavity of its former matrix. Agates have been found in sedimentary rocks in limestone or dolomite. If a silica-rich fluids are able to penetrate into these cavities agates can be formed. A Mexican agate, showing only a single eye, has received the name of cyclops agate. Included matter of a green, red, black or other color or combinations embedded in the chalcedony and disposed in filaments and other forms suggestive of vegetable growth, gives rise to dendritic or moss agate. Dendritic agates include fern-like patterns formed due to the presence of iron oxides. Other types of included matter deposited during agate-building include sagenitic growths and chunks of entrapped detritus. Agate fills a void left by decomposed vegetatable material such as a tree limb or root and is called limb cast agate, due to its appearance. Enhydro agate contains tiny inclusions of water, sometimes with air bubbles.

Turritella agate is formed from silicified fossil Elimia tenera shells. E. tenera are spiral freshwater gastropods with spiral shells composed of many whorls. Coral, petrified wood and other organic remains or porous rocks can become agatized. Coldwater agates, such as the Lake Michigan Cloud Agate, did not form under volcanic processes, but instead formed within the limestone and dolomite strata of marine origin. Like volcanic-origin agates, Coldwater Agates formed from silica gels that lined pockets and seams within the bedrock; these agates are less colorful, with banded lines of grey and white chalcedony. Greek agate is a name given to pale white to tan colored agate found in Sicily, once a Greek colony, back to 400 BC; the Greeks used it for making jewelry and beads. Brazilian agate is found as sizable geodes of layered nodules; these occur in brownish tones interlayered with gray. Quartz forms within these nodules, creating a striking specimen when cut opposite the layered growth axis, it is dyed in various colors for ornamental purposes.

Certain stones, when examined in thin sections by transmitted light, show a diffraction spectrum due to the extreme delicacy of the successive bands, whence they are termed rainbow agates. Agate coexists with layers or masses of opal, jasper or crystalline quartz due to ambient variations during the formation process. Lace agate is a variety that exhibits a lace-like pattern with forms such as eyes, bands or zigzags. Crazy lace agate, found in Mexico, is brightly colored with a complex pattern. Blue lace agate is found in Africa and is hard. Polyhedroid agate is agate; when sliced, it shows a characteristic layering of concentric polygons. Polyhedroid agate is thought to be found only in Brazil, it has been suggested that growth is not crystallographically controlled but is due to the filling-in of spaces between pre-existing crystals which have since dissolved. Other forms of agate include Holley blue agate, a rare dark blue ribbon agate only found near Holley, Oregon.

The Pennsylvania Army National Guard, abbreviated PAARNG, is part of the United States Army National Guard and is based in the U. S. Commonwealth of Pennsylvania. Together with the Pennsylvania Air National Guard, it is directed by the Pennsylvania Department of Military and Veterans Affairs; the PAARNG is present in 87 communities across the Commonwealth. The PA National Guard traces its lineage back to the militia organized by Benjamin Franklin in 1747 known as the Associators. Franklin organized artillery and infantry units to defend the city of Philadelphia against French and Spanish privateers; the first meeting of the Associators occurred on 21 November 1747, on 7 Dec. 1747, the enlistees and officers were formally commissioned by the Provincial Council President, Anthony Palmer. On that day, hundreds of armed Associators presented themselves to Palmer at the Philadelphia Courthouse. Official National Guard webpages state that'he wisely stated their activities were "not disapproved" and duly commissioned all of them.'Only in 1755 did this volunteer militia gain official status.

On November 25, 1755, the Pennsylvania Assembly passed the Militia Act of 1755. This measure'legalized a military force from those who were willing and desirous of being united for military purposes within the province.' This was as a result of citizens' pleas for protection from the French and Indians on the western borders. Two years a compulsory militia law was enacted. All males between 17 and 45 years of age, having a freehold worth 150 pounds a year, were to be organized into companies; every enrolled militiaman was required to appear for training, arming himself, on the first Mondays of March, June and November. In 1793, the Governor of Pennsylvania, Thomas Mifflin established the Adjutant General's Office to provide for "a new system for the regulation of the militia." The next year, Pennsylvania contributed 4,000 militiamen to a four-state force which quelled the Whiskey Rebellion in the western part of the state. Amongst the force were men of the First Troop Philadelphia City Cavalry, the oldest continuously serving U.

S. Army unit; the War of 1812 drew 14,000 Pennsylvanians into active service. During the war, the ancestors of three present day PA ARNG units gained campaign credit. Today those ARNG units are the 103rd Engineer Battalion, the 111th Infantry Regiment, the Headquarters & Headquarters Troop, 2nd Squadron, 104th Cavalry Regiment. Before the Battle of Lake Erie, an artillery company provided volunteers to serve as cannoneers aboard Commodore Perry's ships; that unit is known today as Wilkes-Barre's 109th Field Artillery Regiment. The Washington Grays of Philadelphia was a Volunteer regiment which functioned during war; the Regiment was formed in 1822 and was integrated into the Pennsylvania National Guard in 1879. At the start of the American Civil War in April 1861, five units from the Lehigh Valley raced to Washington, D. C., under threat, in response to an urgent plea from Congress. President Lincoln proclaimed them the "First Defenders"—an honor still borne by their descendants in varied PA National Guard units.

Over 360,000 Pennsylvanians served in the Union Army, more than any other Northern state except New York. Beginning with President Abraham Lincoln's first call for troops and continuing throughout the war, Pennsylvania mustered 215 infantry regiments, as well as dozens of emergency militia regiments that were raised to repel threatened invasions in 1862 and 1863 by the Confederate States Army. Twenty-two cavalry regiments were mustered, as well as dozens of light artillery batteries. In 1870, the name "militia" was dropped, the force became by state law the "National Guard of Pennsylvania." In 1879, the Pennsylvania National Guard established a division, organized in a fashion not approved by the War Department. The keystone was prescribed as the designated symbol of the National Guard of Pennsylvania on 27 August 1879; the Pennsylvania National Guard was mobilized for the Spanish–American War and the Pancho Villa Expedition. When the United States Army created the Spanish War Service and Mexican Border Service Medals, Major General Charles M. Clement was designated as the first official recipient of each, in recognition of his status as the longest-tenured National Guard officer eligible for the medals at the time they were authorized.

Clement served in the Pennsylvania National Guard from 1877 to 1917, commanded the 28th Infantry Division at the start of World War I. During the mobilization after the U. S. entry into World War I in 1917, a number of separately numbered Pennsylvania infantry regiments were given U. S. Army designations, thus the 109th Infantry Regiment, the 110th Infantry Regiment, the 111th Infantry Regiment, the 112th Infantry Regiment were established. These regiments formed the two brigades of the newly designated 28th Division, which saw war service in Europe. Alongside the four regiments of infantry were created four machine-gun battalions; the 104th Cavalry Regiment was formed on 1 June 1921 by reorganization of the 8th Infantry, PA ARNG. It became a part of the 21st Cavalry Division. On 1 May 1922, elements of the machine gun battalions which had served in World War I were reorganized as the 213th Coast Artillery. On 17 February 1942, as part of the triangularization of Army divisions, the previous 103rd Engineer Regiment was broken up and the 103rd Engineer Battalion established.

The other battalion of the regiment became the 180th Engineer Battalion. After being activated in February 1941, the 28th Infantry Division was reorganized in February 1942, the 111t

Stanley T. Sigman is the former president and chief executive officer of wireless at AT&T, the United States's largest wireless provider. A graduate of West Texas State University in Canyon, Sigman began his career with Southwestern Bell Telephone as a stockman in Hereford, Texas, in 1965. A long-time wireless industry leader, Sigman has held leadership positions at SBC Communications, where he helped start SBC's wireless business in the mid-1980s, managed its expansion into one of the largest wireless businesses in the nation, directed its integration into BellSouth's wireless group to form Cingular Wireless in 2001. Prior to joining Cingular, Sigman served as group president and chief operating officer for SBC Communications, responsible for the company's wireline and wholesale operations. Sigman's career has included leading key business units for SBC, including Long Distance, Global Accounts, Sterling Commerce, DataComm, Web Hosting, eCommerce, TRI, Network Planning and Engineering, Network Operations and Consumer Marketing and Operator Services.

Sigman has been long regarded as a wireless industry visionary as well as a champion for wireless safety and technology. He serves as chairman emeritus of the board of directors of the Cellular Telecommunications and Internet Association; the CTIA is the international organization representing all sectors of wireless communications—cellular, personal communication services, enhanced specialized mobile radio. In September 2004, Sigman was appointed to the President's National Security Telecommunications Advisory Committee by President George W. Bush. In its advisory role to the President, the NSTAC provides industry-based analyses and recommendations on a wide range of policy and technical issues related to telecommunications, information assurance, infrastructure protection, other national security and emergency preparedness matters. In December 2004, Sigman was named RCR Wireless News "Person of the Year," in part for his orchestration of the Cingular Wireless acquisition of AT&T Wireless, creating the largest cellular wireless carrier in the US.

Sigman has been named a member of Atlanta Alexis de Tocqueville Society in recognition of his service and commitment to the United Way. He is a member of the Georgia Research Advisory Board and the Georgia Institute of Technology Advisory Board. Sigman announced his retirement as CEO of AT&T Mobility on October 11, 2007, he remained with AT&T Mobility until the end of the calendar year to assist with the leadership change. Ralph de la Vega took his place as CEO. In October 2010, Sigman was inducted into the Wireless History Foundation Hall of Fame. Steve Jobs attended the induction ceremony. After retiring, Sigman founded Namgis Quarter Horses in Texas. A division of his Santa Cruz Ranch, Namgis Quarter Horses, includes a state-of-the-art breeding and training facility for American Quarter Horse roping horses and barrel racing horses