THE MINERAL CLINOHEDRITE

  • Chemistry: CaZnSiO4 - H2O , Hydrated Calcium Zinc Silicate.
  • Class: Silicates
  • Subclass: Nesosilicates
  • Group: Euclase
  • Uses: A very minor ore of zinc and as mineral specimens.
  • Specimens

Clinohedrite is one of the 70 some fluorescing minerals from Franklin and Sterling Hill, New Jersey. It will fluoresce a nice orange-yellow color under short-wave ultra-violet light. This fluorescent color is in striking contrast to the normal color of clinohedrite. Under normal light, clinohedrite is white or colorless. It is one of several good fluorescing minerals from Franklin. The following table shows the more common fluorescing minerals with their respective fluorescing colors, from Franklin and Sterling Hill, New Jersey.

Mineral: Fluoresces: Mineral: Fluoresces: Mineral: Fluoresces:
Barite white Esperite yellow Margarosanite pale violet
Calcite red Fluorite Violet Willemite green
Clinohedrite orange-yellow Hardystonite Violet-blue Wollastonite red

These minerals are sometimes found in association with each other and can make for wonderfully colorful fluorescent specimens. The combination of clinohedrite, hardystonite and willemite is considered a classic. Fluorescence occurs when the ultraviolet light (invisible to humans) imparts energy to some of the atoms in the mineral. This energy is converted by the atoms into visible light that we can then see.

Clinohedrite belongs to an unusual symmetry class called the Domatic Class, of the monoclinic system. This class has only a few members and is characterized by the only symmetry element being a solitary mirror plane. Clinohedrite is a product of the metamorphism of zinc minerals, such as hemimorphite or smithsonite, that were caught up in the regional metamorphism that created the wonderful Franklin and Sterling Hill sites. Clinohedrite is now only found at Franklin and Sterling Hill, New Jersey. A discovery of clinohedrite at Christmas Mine, Gila County, Arizona produced pale violet delicate sprays, but only a few specimens have ever been recovered.

PHYSICAL CHARACTERISTICS:

  • Color is white to colorless and violet.
  • Luster is vitreous to dull.
  • Transparency: Specimens are translucent to opaque.
  • Crystal System is monoclinic; m.
  • Crystal Habits include massive and lamellar specimens. Rare individual crystals are prismatic and at the Arizona locality aggregates formed sprays of acicular crystals.
  • Cleavage is perfect in one direction (pinacoidal).
  • Hardness is 5.5.
  • Specific Gravity is approximately 3.2 - 3.4 (slightly above average)
  • Streak is white.
  • Other Characteristics: Fluoresces an orange-yellow color under short-wave UV light.
  • Associated Minerals include willemite, zincite, franklinite, apophyllite, kinoite, stringhamite, esperite, calcite and especially hardystonite.
  • Notable Occurrences include its type locality: Trotter Mine, Franklin as well as Sterling Hill, New Jersey and at the Christmas Mine, Gila County, Arizona, USA.
  • Best Field Indicators are fluorescence, associations, locality and cleavage.
CLINOHEDRITE specimens:
(hover for more info)
CLINOHEDRITE specimen clh-1
$ 90.00
Dims: 5.5 x 3.5 x 2.9" (13.9 x 8.8 x 7.3 cm)
Wt: 2 lbs., 11.0 oz. (1.219 kg)
Franklin, New Jersey, U.S.A.
Under normal lighting, the massive Clinohedrite embedded in this specimen is essentially impossible to isolate- it is simply a pale brown mineral among other pale brown minerals that are embedded in a mottled brown rock. When exposed to shortwave ultraviolet light, however, one can easily see this mineral by its yellow-orange fluorescent glow. It shows no evidence of crystal form and has a dull luster. Among it are other nondescript minerals, such as willemite and hardystonite- these glow under u/v light also, with respective bright green and dull violet colors. The most easily seen mineral, in fact, is franklinite, which has a black color and submetallic luster, and does not glow under u/v light.
no photo
clh-1 ($ 90.00)
Franklin, New Jersey, U.S.A.
CLINOHEDRITE specimen clh-2
$ 52.00
Dims: 2.48x1.97x1.14" (6.3x5.0x2.9cm)
Wt: 6.55oz (185.5g)
Franklin, New Jersey, USA
This mottled brown chunk of rock from the mines in Franklin, NC, shows nothing of interest under normal light. Under short-wave ultraviolet, however, two minerals glow. Bright green reveals the presence of willemite (barely visible in the image), and a yellow-orange glow reveals the presence of clinohedrite (the color is slightly different and less intense than the orange that the local calcite can glow). Unfortunately, the orange glow of the clinohedrite, while easy to see with a human eye, is not picked up by my camera. The clinohedrite is only present on one face of the specimen.
no photo
clh-2 ($ 52.00)
Franklin, New Jersey, USA
 

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