Museum Quality Hemimorphite Mineral Specimen -OVER 10 LBS!!! Magnificent Sample!

Description

Museum Quality Hemimorphite Mineral Specimen -OVER 10 LBS!!! Magnificent Sample!
This 4901 gram specimen is from the Santo Niño Mine, Santa Maria del Oro, Durango, Mexico.
It measures approximately 10.5 x 8 x 4".  There are 6 crevasses in the front of the piece, 4 on the right side and 2 on the bottom, all
engulfed and surrounded
by Hemimorphite.
This specimen has a flat base and stands on its own for an incredible display in many different orientations.
Hemimorphite Background Information
Hemimorphite most frequently occurs as the product of the
oxidation
of the upper parts of
sphalerite
bearing ore bodies, accompanied by other secondary minerals which form the so-called
iron cap
or
gossan
. Hemimorphite is an important
ore
of zinc and contains up to 54.2% of the metal, together with silicon, oxygen and hydrogen.
Hemimorphite
, is
Zn
4
(
Si
2
O
7
)(
OH
)
2
·H
2
O
, a component of
calamine
. It is a
sorosilicate
mineral
which has been historically mined from the upper parts of
zinc
and
lead
ores
, chiefly associated with
smithsonite
, ZnCO
3
. They were assumed to be the same mineral and both were classed under the same name of
calamine
. In the second half of the 18th century it was discovered that these two different minerals were both present in calamine. They closely resemble each other.
The silicate was the rarer of the two, and was named hemimorphite, because of the hemimorph development of its
crystals
. This unusual form, which is typical of only a few minerals, means that the crystals are terminated by dissimilar faces. Hemimorphite most commonly forms crystalline crusts and layers, also massive, granular, rounded and reniform
aggregates
, concentrically striated, or finely needle-shaped, fibrous or stalactitic, and rarely fan-shaped clusters of crystals.
Some specimens show strong green
fluorescence
in shortwave
ultraviolet
light (253.7 nm) and weak light pink fluorescence in longwave UV.
Physical Properties
Lustre:
Sub-Adamantine, Vitreous, Sub-Vitreous, Greasy, Silky, Pearly
Transparency:
Transparent, Translucent
Colour:
Colorless, white, pale blue, pale green, gray, brown
Streak:
White
Hardness:
4½ - 5 on
Mohs scale
Tenacity:
Brittle
Cleavage:
Perfect
Perfect on {110}, poor on {101}, {001} rare
Fracture:
Irregular/Uneven, Sub-Conchoidal
Density:
3.475 g/cm
3
(Measured)    3.484 g/cm
3
(Calculated)