Rock Garden - calite (red/orange/green/white), aragonite (yellow/gold), and hyalite (green)

Fluorescent Minerals from Southern Arizona

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The fluorescent rocks displayed below were collected from a single mine in the mountains of southern Arizona. The rocks consist of calcite, aragonite, and barite with minor amounts of opal, wulfenite, and amphiboles. The fluorescence is the result of minor impurities in the minerals slightly altering chemical bonds in the crystal structures of the minerals.

The Paleozoic limestone host rock was heated and brecciated as a result of the nearby intrusion of magma. Tremolite and muscovite replaced silty layers in the limestone. At least two episodes or pulses of hydrothermal fluids passed through the limestone, one of which carried the trace element(s) responsible for the fluorescence. The hydrothermal alteration of the limestone resulted in the dissolution of portions of the limestone and deposition of calcite veins, overgrowths, and cavity fillings in the rock. A thin layer of hyalite opal was deposited over the calcite. The limestone was later chemically weathered, again leading to dissolution of the rock and the deposition of aragonite (travertine) in dissolution cavities.

Mineral List (by relative abundance)
  • Calcite (S/L/P)
  • Aragonite (S/L/P)
  • Barite
  • Tremolite (S)
  • Muscovite
  • Quartz
  • Hyalite Opal (S)
  • Cerrusite
  • Psilomelane
  • Hematite
  • Goethite
  • Wulfenite
  • Galena
  • Pyrite
  • Hornblende
  • Biotite
  • Rhodocrocite
  • Smithsonite
  • Sphalerite
  • Hydrozincite (S)
  • Manganocalcite? (S/L)
S = shortwave, L= longwave, P = phosphorescent

The rocks were photographed under shortwave and longwave ultraviolet light. Unless noted, any blue fluorescence showing in the photos is an artifact of the camera sensor and is white or gray to the naked eye. Bright blue specs are dust particles.

Mouse over the images to read the descriptions. Maximum dimensions given in centimeters.

Red/orange limestone with orange and gray calcite overgrowths; 28 cm

Above rock, white light

Dark limestone, orange calcite veins, and yellow travertine; 15 cm

Above rock, white light

Dark limestone, orange calcite veins, yellow and gold travertine, and bright green opal; 33 cm

Above rock, white light

Calcite overgrowths with green hyalite opal under white, longwave, and shortwave light; 20 cm

Above rock, side view; 20 cm

Dark limestone, orange calcite veins, yellow, gold, and green travertine; 25 cm

Above rock, white light

Limestone and calcite veins with green hyalite opal under white, shortwave, and longwave light; 13 cm

Travertine stalagmite, white light Travertine stalagmite, shortwave light; 6 cm

Limestone, calcite, and aragonite veins under white, shortwave, longwave, and short+longwave light; 15 cm

Calcite with manganese oxide spheres, field of view is 8 cm

 

Orange and white calcite with green opal on limestone, white calcite is highly phosphorescent; 30 cm

Orange calcite with green opal; field of view is 5 cm

 

Calcite with green opal coating; field of view is 2.5 cm

 

Orange, pink, and yellow calcite with manganese spheres on limestone; 15 cm

 

Orange calcite and green opal on limestone;  13 cm

Pink calcite, yellow and green aragonite; 76 cm

 

Orange calcite, yellow and green travertine; 4 cm

 

White and orange calcite; 10 cm

 

Orange calcite showing green hyalite coating, yellow travertine; 2.5 cmGreen hyalite on red calcite with yellow travertine; 5 cm

 

Orange calcite, green hyalite, yellow travertine, green aragonite; top 28 cm, middle 18 cm, bottom 8 cm

All pieces from mine except blue fluorite in foreground; field of view 150 cm

 

Nikon D90, ISO 250, f/13, 30secs, focal 24mm; field of view is 90 cm

This photo compares the fluorescence of the Arizona specimens to a small specimen from Franklin, NJ under shortwave light.  The gray arrow points to the Franklin specimen which shows orange calcite and green willemite.  The Franklin specimen is about five centimeters wide.


Petrographic Thin Sections

Slice through specimen used to prepare thin section below; 5 cm

Below are views of a petrographic thin section, ~60 microns in thickness, of the above rock. We are preparing more thin sections and will add them to this page as they are completed.

Thin section under white light; field of view is 2.7mmThin section under shortwave light; field of view is 2.7mm

Thin section under white light; field of view is 2.7mmThin section under shortwave light; field of view is 2.7mm

Thin section under shortwave light; field of view is 2.7mmThin section under shortwave light; field of view is 2.7mm

Below is a thin section of a sample taken from a small prospect near the mine. These rocks show a "bleeding" fluorescence forming halos around the host limestone. The white calcite is highly phosphorescent while the orange calcite shows no phosphorescence

Calcite with diffuse, bleeding fluorescence; 5 cm

Fluorescent halo in calcite formed around sulfide body; field of view is 1.4mm

Below is a thin section of a sample showing green fluorescing opal in calcite. Note the difference in calcite crystal habit on either side of opal.

Green fluorescing opal layer in calcite; field of view is 1.4mm


Pictures from the Mine

The source mine was worked for metals in the late 19th through early 20th century. The mine dump is the source of all the rocks above.

Mine dump in daylight, most of the rocks fluoresce

Mine dump under short/longwave light

Mine dump under short/longwave light

Mine dump under short/longwave light

Mine dump under short/longwave light

Red and orange calcite, yellow aragonite, and green hyalite under shortwave light

 

The bluish white fluorescing mineral below is hydrozincite on sphalerite, a first for this location.

Orange calcite, green hyalite, yellow aragonite, and blue/white hydrozincite under shortwave light

 

Mine dump under shortwave and white light; field of view 1.75m


Other Locations Around Southern Arizona


Miller Canyon, Huachuca Mountains, AZ

The specimens below come from a zinc deposit in Miller Canyon in the Huachuca Mountains of Arizona.  This is a well known locality for fluorescent minerals.

 

Red/orange calcite with green willemite; shortwave; 18 cm

 

Tan sphalerite, purple smithsonite, green willemite; longwave plus shortwave; 15 cm

 

Red/orange calcite, green willemite, and blue/grey hydrozincite; shortwave; 10 cm

 

Red/orange calcite with green willemite; shortwave; 5 cm

A rarity from Miller Canyon is blue willemite.  The blue willemite from Miller Canyon tends to form compact crystals and fluoresce more strongly and phorphoresce longer than the more common willemite coatings shown in the specimens above.  The cause of the blue coloring is currently undetermined.

Blue willemite, center crystal is 2 mm in length.

 

Blue willemite crystal, 8 mm in length; white light and shortwave.


Fluorescent Quartz Crystals!

The quartz crystals below weathered out of a Paleozoic limestone.  The limestone has been partially recrystallized to a marble.   So far, we have found only a small number of these fluorescing quartz crystals in the float, none in outcrop.  The activator is likely uranium and appears to be restricted to a thin overgrowth on the otherwise clear quartz crystals.

Green fluorescing quartz on clear quartz, yellow caliche on calcite; shortwave; field of view is 2.5 cm; stacked from 13 images

 

Green fluorescing quartz on clear quartz; shortwave; field of view is 1 cm

 

Green fluorescing quartz on clear quartz with yellow caliche; shortwave; field of view is 2.5 cm


Fluorite!

These fluorite octohedra occur in outcrop in a vein filling with goethite included druzy quartz.  Host rock is Paleozoic limestone.

Fluorite octohedra with  cubic overgrowths; longwave; individual crystals are 3-8 mm

 

Same view as above under longwave and white light

 

From the same locality as the octohedra above, these specimens show a brecciated limestone, likely fault gouge ,with fluorite veins which were themselves brecciated and then infilled with calcite veins.  The calcite veins show orange under shortwave UV and white or pale yellow under longwave UV. Yellow caliche is more recent and likely formed post-mining.

Blue fluorite, orange/white calcite; short/longwave; 15 cm

 

Blue fluorite, orange/white calcite, yellow caliche; short/longwave; 6 cm

 

Blue fluorite, orange/white calcite, yellow caliche; short/longwave; 25 cm

 

Blue fluorite, orange/white calcite; short/longwave; 12 cm

 

Blue fluorite, orange/white calcite, yellow caliche; short/longwave; 20 cm

 

Mine arch showing fluorite and calcite in place. Arch is 2.5 m in vertical dimension


Scheelite!

Quartz and bornite specimen with accessory calcite and scheelite from skarn hosted in Paleozoic limestone and quartzite.

Blue-white fluorescing scheelite in quartz and bornite; shortwave and white light, 10 cm


Notes on Photography

The photos on this page were taken using Nikon D90, D5100, Lumix LX5, and Sony RX100 cameras. Exposure times range from 3 to 60 seconds. See the exif data for each photo for more information on exposures. For some of the photos minor sharpening, lightening, and contrast enhancement was applied to render the images as true to the naked eye appearance of the specimens as possible. A variety of white balance settings were employed. Of the white balance methods tested, using a color temperature of 7000K was found to produce images with the closest match to the naked eye.  Thin section photomicrographs were taken under an Olympus-Elgeet POS petrographic microscope with a Nikon D90. Quartz crystal photomicrographs were taken under a LOMO MBC-10 stereo microscope with a Nikon D5100. All photos taken using a Way Too Cool 9 watt dual shortwave/longwave ultraviolet lamp and/or a MinerShop 18 watt shortwave lamp.

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All images ©2012, 2013, 2014, 2015, 2016 Daniel Moore