Acicular Aragonite
Contributed by: Daniel C. Montero
minID: 3LG-3PN
Date: May 6th, 2026
Locality: La Serna Quarry (La Tinaja Quarry), La Serna, Pantoja, Toledo, Castile-La Mancha, Spain (See on Mindat)
Size: 20 x 22 mm
Description:
Acicular Aragonite "aka" Aragonito de Pantoja.
Deposit located in the municipality of Pantoja in Toledo. This municipality is approximately 50 km from Madrid, the capital of Spain. The aragonite of Pantoja is a calcium carbonate that crystallizes in the orthorhombic system, the crystals are acicular and radial forming small urchins, characteristic is that under ultraviolet light they give off an intense light, their color oscillates from the color honey or orange-yellowish, white. Its transparency will depend on the thickness of its needles (crystals). The measurements are variable, ranging from hedgehogs of a few millimeters to several centimeters (3 or 4). At the geological level we can mention that these deposits are the most distal facies of the alluvial fans that started from the Sierra and Montes de Toledo during the Middle Tertiary. As collectors and researchers we try that minerals that are not recognized as the stars of the world of collecting are shown with all their charm and mystery.
Under UV light they respond with intense fluorescence and long phosphorescence in LW - MW - SW.
Originally posted by Daniel C Montero on Nature's Rainbows in 2018.
Summary of luminescence responses:
Aragonite (Mindat) (RRUFF)
- Fluorescence under Longwave (365nm LED) UV light: White
- Fluorescence under Midwave (305nm Lamp/Mercury) UV light: White
- Fluorescence under Shortwave (254nm Lamp/Mercury) UV light: White