What is the scientific name of the rock porphyry?
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http://en.wikipedia.org/wiki/Porphyry_(geology)
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that'll be chalcedony. it differs from quatrz in it's shape, as it usually occurs in botryoidal masses, whereas quartz occurs more in hexagonal prisms. chalcedony is similar to opal, but can be distinguished by its higher specific gravity. it can be formed as a dehydration product of opal, hence the connection. the colour is highly variable, as it can be white, blue, red, green, brown or black, and varieties of chalcedony include jasper, agate, chrysoprase, onyx and carnelian. it's formed in rock cavities, especially lavas, and it develops at relatively low temperatures, whereas quartz occurs in any rock type, and usually formed at higher temperatures
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Ruby is not a mineral in its own right, it is a variety of the mineral CORUNDUM. Ruby is the name given to corundum (aluminum oxide) which is coloured red by having small amounts of chromium as an impurity (blue sapphire is corundum with iron and titanium). Ruby is found in many areas around the world but only in small ammounts. Ruby good enough to cut into gemstones is VERY rare. So rare in fact that the price the prices per carat of fine rubies are the highest of all gemstones including diamonds.
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Answering the question would be easier if I knew which type of mineral you were looking for.  Try looking on this link:\n\nhttp://www.rockhounds.com/rockshop/table.shtml\n\nIf you are looking to purchase, there are many people willing to take your money.  For information and more reasonable prices, there are rockshops (non new age) sprinkled through out the country, and the 2 best gems shows are in Denver & Tuscon.\n\nThe next issue is size.  In different mineral species, different sizes are considered large.  For example, quartz crystals up to the size of a gallon jug are found in Mt Ida, AK while selenites have been found in Mexico up to 20 ft tall (note that these are single crystals, not undifferentiated masses).  The largest rhodocrosite is about 6.5 inches per face (in the Denver Natural History Museum), the largest calcite is around 2 foot long (Shifferdecker Museum in Joplin, Mo).  With my friends, I have found a 14" double terminated calcite in Okhlahoma, and a nearly 2 foot selenite in Kansas.\n\nSolution minerals are more typically accessable when compared  with igneous ones, but all the hugest crystals are of igneous origin.  Most of the world record holders are so big thay can never be moved from the mine, unless destroyed.\nIf you seek mineral materiel without reference to single crystals, rough is available in masses shipped in either oil barrels or box cars, usually for industry or amature lapidary work.\n\nIf you are seeking gem materiel, it is unlikely that you can find it for a price within reason, even the synthetics. \n\nIf you are seeking geodes, the warsaw shale is the place to look.  It extends through out the midwest.\n\nThere are groups of rockhounds all over, and we go forth to find exactly what you are seeking.  However, there is actual physical labor involved, and possibly travel costs.  You might consider also speaking a professor with the local college in your area.
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Check this out: http://en.wikipedia.org/wiki/Moon_rocks
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Peridot (pronounced pear-e-doe) is the gem quality variety of forsterite olivine. It is bright yellow-green in color, and has a hardness of 6.5 on Mohs scale. The chemical composition of peridot is (Mg, Fe)2SiO4. Peridot is one of the few gemstones that come in only one color. The depth of green depends on how much iron is contained in the crystal structure, and varies from yellow-green to olive to brownish green. Peridot is also often referred to as "poor man's emerald". Olivine is a very abundant mineral, but gem quality peridot is rather rare. Peridot crystals have been collected from iron-nickel meteorites.\n\nPeridot is found in Arizona, Hawaii, Nevada, and New Mexico, in the US, and in Australia, Brazil, China, Kenya, Mexico, Myanmar (Burma), Norway, Pakistan, South Africa, Sri Lanka, and Tanzania. Peridot of high quality is commercially mined in the eastern lava fields of Saudi Arabia. The largest cut peridot is a 310 carat (62 g) specimen in the Smithsonian Museum in Washington, D.C.. A special variety of peridot from Pakistan is known as "Cashmere" peridot. Due to the large size of the rough stones found there, cutters have successfully created faceted stones of over 100 carats (20 g) from the rough gems of this area.\n\nIt is the birthstone for the month of August. According to folklore, the peridot will bring its wearer success, peace, and good luck. Peridot has been found in Egyptian jewellery from the early second millennium BCE and was mined from the volcanic island of Zebirget, or St. Johns Island, in the Red Sea. Native Hawaiians referred to peridot crystals as the tears of Pele, their goddess of fire\n-----------------\nPeridot is perhaps derived from the French word peritot which means unclear, probably due to the inclusions and cloudy nature of large stones. It could also be named from the Arabic word faridat which means gem. In either case, peridot has been mined as a gemstone for an estimated four thousand years or better, and is mentioned in the Bible under the Hebrew name of pitdah. Peridot gems along with other gems were probably used in the fabled Breastplates of the Jewish High Priest, artifacts that have never been found. The Greeks and Romans referred to peridot as topazion and topazius respectively and this name was later given to topaz, to end the confusion with the two gems. Historical legend has it that peridot was the favorite gemstone of Cleopatra. Pliny wrote about the green stone from Zagbargad Island in 1500 B.C.. Even until recently have jewelers used the term "chrysolite" (latin for golden stone) in referring to peridot gems for some reason. This term has also been used to refer to other gemstones, of a more golden color. \n\nZagbargad (Zebirget) Island has been known as St John's Island and was mined for centuries. Before World War I, this island was extensively mined and produced millions of dollars worth of gems. Since then the mining has been off and on and at present is all but nonexistent. Still, specimens from here are available at times and it certainly is a classic mineral locality. \n\nThroughout time, peridot has been confused with many other gemstones, even emerald. Many "emeralds" of royal treasures have turned out to be peridots! And although peridot is distinctly a different shade of green, many jewelers refer to peridot as "evening emerald". Emerald is a dark green as opposed to a yellow green and always contains inclusions. Other green gemstones confused with peridot include apatite (which is much softer); green garnets (have no double refraction), green tourmaline and green sinhalite (both of which are strongly pleochroic), moldavites (no double refraction) and green zircon (significantly heavier). All of these gemstones rarely have as nice a yellow component to their green color as does most peridot, but darker green peridot can be confusing when good crystal form is not discernible. \n\nPeridot is a beautiful ge
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The official answer is that the rock itself dates clear back to the precambrian. That is OLD, somewhere between 700 and 4700 million years ago.
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Peridot (pronounced "pear-uh-dot" or "pear-uh-doe", IPA: /pɛɹɪdɑːt/ or Fr. /peʁido/) is the gem quality variety of forsteritic olivine. The chemical composition of peridot is (Mg, Fe)2SiO4, with Mg in greater quantities than Fe. The name of the gemstone is believed to come from either the Arabic word faridat meaning "gem" or the French word peritot meaning "unclear." Peridot is one of the few gemstones that comes in only one color. The depth of green depends on how much iron is contained in the crystal structure, and varies from yellow-green to olive to brownish green. Peridot is also often referred to as "poor man's emerald". Olivine is a very abundant mineral, but gem-quality peridot is rather rare. Peridot crystals have been collected from iron-nickel meteorites.
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The term epiphyte refers to any plant that grows upon or attached to another living plant. The term stems from the Greek epi- (meaning 'upon') and phyton (meaning 'plant'). These plants are sometimes called "air plants" because they do not root in soil. However, there are many aquatic species of algae, including seaweeds, that are epiphytes on other aquatic plants (seaweeds or aquatic angiosperms).\n\nOf course there are also parasitic and semiparasitic plants growing on others. The best-known of this is the mistletoe.\n\nAn epiphyte uses photosynthesis for energy and (where non-aquatic) obtains moisture from the air or from dampness (rain and cloud moisture) on the surface of its host.\n\nRoots may develop primarily for attachment, and specialized structures (for example, cups and scales) used to collect or hold moisture.\n\nEpiphytes are not parasitic on their host, growing independently and deriving only physical support. A clear advantage is gained over other herbs restricted to the ground (soil) surface where light is less available in the forest and herbivores are more active. However, epiphytes may grow so thickly as to damage the supporting plant.\n\nThe best-known epiphytes include mosses, lichens, orchids, and bromeliads (such as Spanish moss of the genus Tillandsia), but epiphytes may be found in every major group of the plant kingdom. Assemblages of large epiphytes occur most abundantly in moist tropical forests, but mosses and lichens occur as epiphytes in almost any environment with trees.
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1) Rhyolites that cool too quickly to grow crystals form a natural glass or vitrophyre, also called obsidian\n\n2) amount of silica di-oxide, texture and color\n\n3) gold is found in quartz veins around igneous intrusion via hydrothermal fluid precipitation\n\n4) If we assume a slower but constant rate of cooling, then both minerals could feasibly form well shaped crystals at the same time (phaneritic texture) .  If we assume a slow than fast cooling, then possibly only plagioclase would form (porphyritic texture) due to its position in Bowen's reaction series.
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Granite, forms deep underground\nObsidian, the really dark and smooth black rock\nBasalt, which forms from volcanoes mostly\nPumice, the really light rock that floats on water\n\nand a few others, listed in the source site
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Both are igneous rocks, meaning they formed from molten rock (called magma when it is underground and lava when it is on the surface) and are pretty hard and dense, but the similarities trail off fast from there.\n\nGranite is an intrusive rock, which means it cooled off slowly well underground and crystals had time to grow relatively large.  If the crystals grow really large they call the rock a pegmatite; I've heard of a pegmatite in Russia with feldspar crystals the size of boxcars.\n\nBasalt is an extrusive rock, which means the molten rock flowed out onto the surface and cooled there quite quickly, leaving very little time for crystals to grow.  Some basalts do include some larger crystals that formed while the magma was still underground and moving up (and cooling) relatively slowly.  I've seen basalt from Hawai'i that contains pea-sized lumps of green olivine crystals.\n\nThe two differ chemically as well.  Granites contain more silica, and tend to be lighter in color than basalts.  Basalts tend to be more alkaline.\n\nGranites are associated with relatively low temperatures, around 800 degrees Celsius.  The minerals in basalt typically form at temperatures above 1300 degrees celsius.\n\nGranites are formed in continents , while basalts form at ocean spreading centers, like the mid-Atlantic Ridge, "hot spots", like the one that formed Hawai'i, and sometimes on continents.  Basalt also erupts on land; there are huge masses of basalt in the western United States (the Columbia River basalts) and in western India (the Deccan traps).
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MAGMA is the molten rocks and minerals below the Earth's crust.\n\nLAVA is what we call it when it reaches the surface of the Earth through means such as a volcanic eruption.\n\nLAHAR is what we get when the lava flows into flowing body of water such as rivers and streams.
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"\nAndesite porphyry\nAndesite\nAnorthosite\nBasalt\nBasalt porphyry\nBasalt, vesicular\nDiorite\nDunite\nFelsite\nGabbro\nGranite, Alkali-\nGranite, Plagio-\nGranodiorite\nMonzonite\nMonzonite, quartz\nObsidian\nPeridotite\nPumice\nPyroxenite\nRhyolite\nRhyolite porphyry\nScoria\nSyenite\nVocanic breccia\nVolcanic tuff\n"\n\nApparently Andesite is on the list ;O)
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G: The rock cycle.  See source.
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Sapphirine (one "r") is a rare mineral, a silicate of magnesium and aluminium.Collected by Gem enthusiasts and sometimes cut into sapphire colored gemstones.
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3 basic types of rocks\n\nIgneous Rocks-Igneous rocks are crystalline solids which form directly from the cooling of magma. This is an exothermic process (it loses heat) and involves a phase change from the liquid to the solid state. The earth is made of igneous rock - at least at the surface where our planet is exposed to the coldness of space. Igneous rocks are given names based upon two things: composition (what they are made of) and texture (how big the crystals are).\n\nSedimentary Rocks-In most places on the surface, the igneous rocks which make up the majority of the crust are covered by a thin veneer of loose sediment, and the rock which is made as layers of this debris get compacted and cemented together. Sedimentary rocks are called secondary, because they are often the result of the accumulation of small pieces broken off of pre-existing rocks. There are three main types of sedimentary rocks:\n\nMetamorphic Rocks-The metamorphics get their name from "meta" (change) and "morph" (form). Any rock can become a metamorphic rock. All that is required is for the rock to be moved into an environment in which the minerals which make up the rock become unstable and out of equilibrium with the new environmental conditions. In most cases, this involves burial which leads to a rise in temperature and pressure. The metamorphic changes in the minerals always move in a direction designed to restore equilibrium. Common metamorphic rocks include slate, schist, gneiss, and marble.