Jump to content

Recommended Posts

20 hours ago, Hibby said:

2 questions:

 

is shortwave light the the same as black light?

 

is conglomerate the same as 'pudding rock'?

Hi Hibby... we'll ignore your second question because it has been suitably addressed above. Shortwave light is not the same thing as black light at all.

Light below the wavelength of violet light is described as ultraviolet light. Keep in mind as you read this explanation that ultraviolet (UV) light is invisible to the human eye. Longwave UV peaks at about 360 nanometers, while shortwave UV peaks at about 254 nanometers. Midwave UV light is generally considered to peak at about 312 nanometers. 

"Blacklights" are an inexpensive way for beginners to get started in the hobby as they do produce longwave UV light that will work fine for minerals that happen to fluoresce brightly when exposed to such light. While equipped with a visible light filter, these inexpensive filters are not nearly as effective as the visible light filters incorporated into shortwave, midwave, and longwave UV lamps suitable for observing fluorescent minerals. Hence the visible light inherent to using blacklights can and does frequently overwhelm the longwave UV light effects on fluorescent minerals.

Next basic thing to understand is that most minerals do not fluoresce brightly under longwave UV light. In order to see all the bright colors that make fluorescent minerals so attractive, as a minimum you will require a shortwave UV lamp. As a general rule of thumb, these are considerably more expensive than longwave UV lamps, and also should be used with protective eyewear.  A good battery-powered shortwave UV field lamp is priced comparably with entry level VLF metal detectors. Midwave lamps are usually purchased only by advanced hobbyists, and are at least as expensive as shortwave UV lamps. There are a number of minerals that respond better to midwave UV light than to either shortwave or longwave UV light. Hope this helps to clarify things a bit…

Jim.
 

 

  • Like 3

Share this post


Link to post
Share on other sites

Jim - thanks for such a thorough answer. You even answered questions I hadn't answered yet (but was going to).

  • Like 1

Share this post


Link to post
Share on other sites

Another Q - Do all ammonite fluoresce? I have a giant museum quality specimen and I am curious if it would glow like that.

IMG_2151.JPG

  • Like 1

Share this post


Link to post
Share on other sites
2 hours ago, Hibby said:

Another Q - Do all ammonite fluoresce? I have a giant museum quality specimen and I am curious if it would glow like that.

IMG_2151.JPG

Hi Hibby… I can’t speak to this topic from direct experience, but I did take a moment (while viewing the Pittsburgh Penguins hockey game) to look on the Internet for an answer to your question. I was curious to learn more too.

According to The Fossil Forum, ammonite fluorescence will vary with the type of mineral replacement that has formed the fossil. That makes perfect sense, hence some ammonites will simply not fluoresce, some will fluoresce only under short wave UV light, and some only under longwave UV light.

Of course it goes without saying that the light intensity makes a difference as to how well potentially fluorescent minerals respond to UV light. Hope that helps...

Jim.
 

  • Like 2

Share this post


Link to post
Share on other sites

One interesting thing to note about mineral replacement in some ammonites I have seen (and petrified wood too), if the conditions are right, the replacement mineral is cryptocrystaline quartz with opalescence.  Essentially you get a similar effect to fluorescence, but without the need for any wavelength of uv light.  It is like an enourmous fossil that is also an opal.  It wouldn't surprise me if the uv effect adds to the brilliance, though I know nothing about that.

Nice specimen Hibby.

 

  • Like 2

Share this post


Link to post
Share on other sites
20 hours ago, Jim Hemmingway said:

Hi Hibby... we'll ignore your second question because it has been suitably addressed above. Shortwave light is not the same thing as black light at all.

Light below the wavelength of violet light is described as ultraviolet light. Keep in mind as you read this explanation that ultraviolet (UV) light is invisible to the human eye. Longwave UV peaks at about 360 nanometers, while shortwave UV peaks at about 254 nanometers. Midwave UV light is generally considered to peak at about 312 nanometers. 

"Blacklights" are an inexpensive way for beginners to get started in the hobby as they do produce longwave UV light that will work fine for minerals that happen to fluoresce brightly when exposed to such light. While equipped with a visible light filter, these inexpensive filters are not nearly as effective as the visible light filters incorporated into shortwave, midwave, and longwave UV lamps suitable for observing fluorescent minerals. Hence the visible light inherent to using blacklights can and does frequently overwhelm the longwave UV light effects on fluorescent minerals.

Next basic thing to understand is that most minerals do not fluoresce brightly under longwave UV light. In order to see all the bright colors that make fluorescent minerals so attractive, as a minimum you will require a shortwave UV lamp. As a general rule of thumb, these are considerably more expensive than longwave UV lamps, and also should be used with protective eyewear.  A good battery-powered shortwave UV field lamp is priced comparably with entry level VLF metal detectors. Midwave lamps are usually purchased only by advanced hobbyists, and are at least as expensive as shortwave UV lamps. There are a number of minerals that respond better to midwave UV light than to either shortwave or longwave UV light. Hope this helps to clarify things a bit…

Jim.
 

 

Thanks for your help Jim. Yes, my 60 watt short wave cost me $750 several years ago

  • Like 1

Share this post


Link to post
Share on other sites

Hibby, look like nice Madagascar fossils,  good chance that the light materials on your fossils will fluoresce if they are polished. If they have been sprayed with clear they will not. I don’t know what the host rock is but looks man made 

  • Like 3

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Similar Content

    • By phoenix
      I bought another Michigan copper nugget the other day.      I love this kind of stuff.      This one goes 235 grams.  7½ ounces feels really nice in your hand



    • By Steve Herschbach
      Good article and photos....
      https://www.usatoday.com/story/money/2018/02/12/how-one-african-mine-produced-nearly-1-000-carat-diamond-stunner/319678002/
    • By Gerry in Idaho
      Know your Rocks.
      This highly desired collectors piece was found by one of my customers with a Fisher Gold Bug-2.
      If you did not know what to look for you'd probably toss the rock aside thinking "just another iron stone hot rock".  When you see a good variety of colors and minerals, its time to slow down.
      Here is a 1 of a kind tree shape gold specimen or Dagger.
      Thanks to my customers for sharing your photos of Success with me.



    • By Rick Watkins
      Hi guys,
      got a question with octahedral gold, I have been trying to get a clear picture of how this is formed.
      Can someone explain how this is formed, I have looked this up but cant get a clear picture of makeup.
      I realized recently that I have found a octohedral piece of gold from a recent hunt, pretty small but nice.
      it is around 1/16 of an inch. Anyone with info on this I would appreciate it. Thanks Rick
    • By Steve Herschbach
      A California woman says she found a 1½ carat diamond while mining gold near the Sierra Nevada foothills town of Foresthill.
      “I was like ‘Oh, my god, I found a diamond,’  ” said Jillian Kelly.
      Kelly, 49, left her Silicon Valley career to take up mining 10 years ago and wrote ‘The Miracle Miner: My Life as a Female Gold Miner.” The uncut semi-clear pebble-sized stone is about width of a dainty pinky finger.
      The rest of the story with photos at The Sacramento Bee
    • By 1515Art
      Found a copper ore nodule scanning some mine tailings in n Nevada, 94 on the Deus and very heavy. XRF readings at the local pawn shop were; Fe 1.53%, Zn 27.37%, Sn .632%, Cu 67.68%, Pb 2.37%. Sure wish there was a little Au in there, next time I wish. Or, could this just be a melted fitting buried in the tailing pile way in the desert high on the side of a hill?



×