紫外線(UV)是波長比可見光短的光,范圍從大約25nm(納米)到400nm。盡管我們看不到紫外線,但是當可見光暗淡或不存在時,我們可以看到紫外線對熒光礦物的絢麗多彩效果。紫外線的光范圍分為四類:遠紫外線(25nm至250nm);紫外線。短波(250nm至300nm); 中波(300nm至350nm); 和長波(350nm至400nm)。其中,短波和長波紫外線是熒光礦物收集者最感興趣的紫外線。盡管有相當數量的礦物對長波(也稱為黑光)產生響應,但百分之九十的礦物對短波輻射的響應強烈。某些礦物質會對兩者產生響應,兩種波長發出的不同顏色可以幫助識別樣本。
紫外線除了在熒光礦物質中引起彩色顯示外,還有許多用途。短波,中波和長波紫外線在許多實驗室應用中至關重要,例如色譜法和生物樣品分析。短波和中波紫外線可殺死許多細菌,因此可用于滅菌以及各種醫學治療。地毯清潔公司使用長波紫外線來定位寵物尿漬(您也可以這樣做,使用無底盒或黑色懸垂布提供必要的黑暗度)。紫外線的安全性,法醫和工業質量控制應用很常見。
在紫外線燈的照耀下,許多普通物品發出熒光:牙齒,白襯衫,許多墨水和塑料,曲軸箱油,一些木材-甚至是蝎子,這一事實給不只一個探礦者帶來了麻煩,他們在沙漠中尋找沙漠。晚!但是熒光礦物質的反應激發了收藏家的興趣。方解石在通常的日光下通常是暗淡的白色,可能發出紅色或橙色,粉紅色或綠色的熒光。螢石本身很漂亮,但在紫外線下確實能恢復活力:亮的淡黃色,深綠色,藍綠色,藍色,紫藍色,紅紫色,橙色,奶油色和藍白色。
礦物顯示的熒光顏色變化通常歸因于被稱為活化劑的雜質。活化劑(在某些情況下,一種或多種活化劑)吸收紫外線,并在反應中發出可見光(彩色)和少量熱量。活化劑錳會使方解石發出紅色或橘紅色熒光。螢石,深綠色;和氟磷灰石,黃色。鈾酰離子可使大多數礦物發出綠色熒光。
有時,活化劑電子會停留在高能狀態,并且在關閉紫外線后,礦物會繼續發光。這稱為磷光。在新澤西州富蘭克林發現的威廉石品種是熒光和磷光礦物的例子,但還有許多其他種類。方解石通常是磷光的。對一些帶有紫外線的礦物質加熱(例如,將其短暫地放在熱水龍頭下)將使磷光更加顯著。
用于此愛好(或激情!)的燈在外觀和功能上與普通熒光燈相似-充滿氬氣和少量汞的玻璃管。電流使水銀發出紫外線。在普通的熒光燈中,燈管內部的涂層將其轉變為可見光。短波管是無涂層的,由特殊的石英或高硅玻璃制成,這是大多數類型的玻璃短波傳輸的一種。長波管是普通玻璃,上面涂有長波發磷光體,而不是可見光。
短波紫外線燈和長波紫外線燈都需要濾光片,以阻擋否則會產生的少量可見光。短波紫外線燈使用一個單獨的濾鏡,該濾鏡必須由一種特殊的玻璃制成(這是使短波燈比長波燈更昂貴的因素之一)。一些長波管將過濾器作為玻璃的一部分,而其他一些則使用單獨的廉價過濾器。
收集熒光礦物質
通常,獲取標本的最令人滿意的方法是自己找到標本。一個很好的開始方法是加入當地的搖滾俱樂部。如果沒有可用的書,或者您更喜歡單獨閱讀,那么一本有關熒光礦物的好書,再加上對您所在地區的指南,可以幫助您入門。始終確保您知道計劃收集的區域的狀態,并在需要時獲得許可!熒光礦產學會是創業者和有經驗的勘探者的良好資源。
可充電6瓦紫外線燈小型手持式6瓦紫外線燈方便攜帶。當您是新手時,它們是一個不錯的起點。更大的6瓦掌上電腦這將使堅定的探礦者更加滿意,因為它們會在幾英尺遠的距離內觸發標本中的熒光,這在夜間出門時會大有裨益。多波段或組合紫外線燈使用戶可以在短波和長波之間切換(LEAC-280L)。盡管可以預期紫外線輸出會有所降低,但這可以大大節省設備成本。
對UV礦物探礦機有用的大多數其他工具是標準的獵犬獵犬:錘子,鑿子,撬桿,野外集塵袋,安全設備等。安全眼鏡或護目鏡特別有用,因為它們可以保護您的眼睛免受短波輻射和碎石的侵害。當然,晚上旅行時,優質的手電筒應與紫外線燈一起放入野外旅行袋或口袋中。
在白天進行勘探時,需要某種方式來創建用于測試可能的熒光樣本的黑暗空間。盡管黑色塑料片做得相當不錯,而且重量輕且價格便宜,但可以使用商用觀察袋。
包裝時(在將放入野戰包之前應做的事,以防止其被砸傷),請先將其包裝在保鮮膜中,或者確保已對打算使用的報紙進行了測試與您的短波和長波燈一起使用,用于熒光染料。
請記住,當您晚上收集時,要小心不要撿起任何發光的蝎子!
LEC-180L/12手持式紫外線燈在12伏直流電或直流電下運行。實際上,這意味著管中的一根細絲會先于另一根磨損。如果在輸出開始變暗時反轉燈管,則可以延長其壽命。
要記住的另一件事-這次是安全建議-短波紫外線是引起曬傷的波長。雖然很難從業余愛好者的燈中獲得足夠的曝光來灼傷皮膚,但是長時間直視短波燈無疑會導致眼睛暫時受損。避免這種情況!只要將短波樣本放在玻璃杯中(但不要放在魚缸中!魚沒有眼瞼,因此根本就不會受到短波輻射的灼傷),則可以安全地顯示短波樣本。
美國路陽上海公司提供多種波段的紫外線燈,歡迎大家咨詢選購。
Ultraviolet (or UV) is light with wavelengths shorter than that of visible light, measuring from about 25nm (nanometers) up to 400nm. Although we can't see ultraviolet light, when visible light is dim or absent we can see ultraviolet's brilliantly colorful effect on fluorescent minerals.
The ultraviolet range of light is divided into four categories: far ultraviolet (25nm to 250nm); short-wave (250nm to 300nm); mid-wave (300nm to 350nm); and long-wave (350nm to 400nm). Of these, short-wave and long-wave UV are the ones of most interest to collectors of fluorescent minerals. Ninety percent of these minerals respond most strongly to short-wave radiation, though a respectable number respond to long-wave (also known as black light). Some minerals respond to both, and the different colors brought out by the two wavelengths can help identify a specimen.
Ultraviolet light has many uses other than causing colorful displays in fluorescent minerals. Short-wave, mid-wave, and long-wave UV are vital in numerous laboratory applications, such as chromatography and the analysis of biological samples. Short-wave and mid-wave UV kill many bacteria, and so are used in sterilization, as well as for a variety of medical treatments. Carpet cleaning companies use long-wave UV to locate pet urine stains (you can do this too, using a bottomless box or black drape to provide the necessary darkness). Security, forensic, and industrial quality control applications for ultraviolet light are common.
Fluorescent Minerals
Under the rays of a UV lamp many ordinary items fluoresce: teeth, white shirts, many inks and plastics, crankcase oil, some woods -- even scorpions, a fact which has caused problems for more than one prospector who was out hunting the desert at night! But it is the response of fluorescent minerals that excites the interest of collectors. Calcite, which is often a dull white in ordinary daylight, may fluoresce red or orange red, pink, or green. Fluorite is pretty on its own, but really comes alive under UV: bright pale yellow, deep green, blue-green, blue, violet-blue, red-violet, orange, cream, and bluish white.
The fluorescent color variations displayed by a mineral are generally due to impurities known as activators. The activator (or activators, in some cases) absorbs ultraviolet radiation, and in reaction emits a combination of visible light (color) and minute amounts of heat. The activator manganese makes calcite fluoresce red or orange-red; fluorite, a deep green; and fluorapatite, yellow. The uranyl ion makes most minerals in which it is found fluoresce some shade of green.
Sometimes the activator electrons get stuck in their high-energy state, and the mineral will continue to glow after the UV light is switched off. This is called phosphorescence. The variety of Willemite found in Franklin, NJ is an excellent example of a mineral that is both fluorescent and phosphorescent, but there are many others. Calcite is often phosphorescent. Applying heat to some UV-charged minerals (by holding them briefly under a hot water tap, for example) will make the phosphorescence even more dramatic.
The UV lamps used for this hobby (or passion!) are similar in appearance and function to ordinary fluorescent lights -- glass tubes filled with argon gas and a little mercury. Electrical current causes the mercury to emit ultraviolet light. In the ordinary fluorescent lamp, a coating on the inside of the tube turns this into visible light. Short-wave tubes are uncoated, and made of a special quartz or high-silica glass, as most kinds of glass block short-wave transmission. Long-wave tubes are regular glass coated with a long-wave-emitting phosphor instead of a visible light-emitting one.
Both short-wave and long-wave tubes require filters to block the small amount of visible light the tubes would otherwise produce. Short-wave tubes use a separate filter, which must be made of a specialized kind of glass (one of the factors that makes short-wave lamps more expensive than long-wave ones). Some long-wave tubes incorporate the filter as part of the glass, while others use a separate, inexpensive filter.
Collecting Fluorescent Minerals
Often the most satisfying way of acquiring specimens is to find them yourself. One good way to start is to join a local rock club. If none is available, or you prefer to go it alone, a good book on fluorescent minerals, combined with a rockhounding guide to your area can get you started. Always be sure that you know the status of the area where you plan on collecting, and get permission when it is needed! A good resource for both the beginning and the experienced prospector is the Fluorescent Mineral Society.
Rechargeable 6 watt UV lampSmall handheld 4 watt UV lamps are convenient and easy to carry. They are a good place to start when you are new to the hobby. The larger 6 watt handhelds will be more satisfying to the committed prospector, as they will trigger fluorescence in specimens from several feet away, a great boon when you are out hunting at night. Multiband or combo lamps allow the user to switch between short-wave and long-wave light. This can provide a significant savings in the cost of your equipment, though some decrease in ultraviolet output can be expected.
Most of the other tools useful to the UV mineral prospector are standard rockhounding tools: hammers, chisels, pry bar, field bag, safety equipment, and the like. Safety glasses or goggles are particularly useful, as they will protect your eyes from short-wave radiation as well as flying rock chips. A good flashlight should go into your field bag or pocket along with your UV lamp(s) for night trips, of course.
Some way of creating a dark space for testing possible fluorescent specimens is necessary when prospecting during daylight hours. Commercial viewing bags are available, though a black plastic sheet does a pretty decent job and is both lightweight and inexpensive.
When wrapping your prizes (which you should always do before you put them in your field bag, to protect them from getting banged up), either wrap them first in plastic wrap, or be sure that you've tested the newspaper you plan to use with your short-wave and long-wave lamps, for fluorescent dyes.
Remember when you're collecting at night to be careful to not pick up any prettily glowing scorpions!
Hints for Using UV Lamps
Handheld UV lamps run on 12 volt DC, or direct current. In practical terms this means one of the filaments in the tube will wear out before the other. If you reverse the tube when the output begins to dim, you can extend its life.
Another thing to keep in mind -- a safety suggestion this time -- is that short-wave UV is the wavelength that causes sunburn. While it is very hard to get enough exposure from a hobbyist's lamp to burn skin, looking directly into a short-wave light for an extended period of time can certainly cause temporary damage to your eyes. Avoid this! Displaying short-wave specimens is safe as long as you have them behind glass (but not in a fish tank! Fish have no eyelids, and thus no protection at all from being burned by the short-wave radiation)