Optical Calcite
(aka)    "Iceland Spar"
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This variety of Calcite is called "Iceland Spar", which is basically clear cleaved fragments of completely colorless (ice-like)
calcite. Originally discovered in and named after Eskifjord, Iceland. The Iceland spar displays the classic cleavage form of
calcite, the rhombohedron. Iceland Spar is used for optical equipment and during World War II it was an extremely important
mineral that was used in the sighting equipment of bombardiers and gunners. Our specimens come from the locations
currently producing the most interesting specimens for collectors. We are always looking for more locales.

“A secret mine in the mountains west of the Salton Sea contained the only available source of a particular calcite crystal
needed to make the famous “Norden Bombsight”.  This transparent crystal formation is also known as Iceland Spar because
it is found in cavities in the solidified lava of which Iceland is made.  The war in Europe had made shipping in the North
Atlantic very precarious and the United States needed another source of this precious commodity.  The Norden bombsight
was one of the most important military secrets of World War II; it made possible the very accurate European bombing raids
which helped bring the war to a close.  It was so advanced that bombardiers had to take an oath to protect its secrecy with
their lives.  Arthur LaLonde remembers that one of his first assignments in the military was to search, with four other men, the
snowy summit of Mt. San Jacinto for the Norden bombsight carried on a plane that had crashed there.  Locals who worked
the mine remember that it was guarded by Marines and worked around the clock.  The mine is now within the boundaries of
Anza-Borrego State Park, north of the Salton City Borrego Springs highway.”
Source:  The Periscope 2001 - Publication of the Coachella Valley Historical Society

Iceland spar demonstrates the unique property of calcite called birefringence (double refraction). Double refraction occurs
when a ray of light enters the crystal and due to calcite's unique optical properties, the ray is split into fast and slow beams.
As these two beams exit the crystal they are bent into two different angles (known as angles of refraction) because the angle
is affected by the speed of the beams. A person viewing into the crystal will see two images ... of everything. The best way to
view the double refraction is by placing the crystal on a straight line or printed word. The result will be two lines or two words
visible through the calcite. The thickness and the angle of the Calcite determines the distance between lines or text as can
be seen in the photos in our listings. Turning or rotating the calcite increases or decreases the space between the two lines
or words (double refraction) that this mineral is famous for. Different sides of the rhomb give different separation  distances
for the double refraction as well. These are very educational and interesting pieces!
Item # 18-GBOPTCAL12193207
129g A Grade Optical Calcite
from Brazil Polished in
Idar-Oberstein

$15
2.00
A Grade 129g Clear Optical Calcite from Brazil, Polished in Idar-Oberstein

We were able to procure a few special specimens in our never ending search for
quality Optical Calcites when we found this Optical Calcite Crystal from Mato
Grosso do Sol, Brazil that was ground and polished in Idar-Oberstein, Germany
(Deutchland).  We have sold many Optical Calcite Crystals over the years from
Mexico, Germany, Madagascar and Brazil. The most popular so far have been
the Brazilian crystals that are polished with beveled edges.  The best of these
Brazilian Calcites are the ones ground and polished by the artisans in
Idar-Oberstein. Of all Optical Calcites we have ever come across, these
Idar-Oberstein calcites are hands down the highest quality clarity with excellent
Birefringence.

This specimen is a beautiful specimen of Idar-Oberstein polished
Brazilian Optical Calcite.

This specimen measures 1.6 x 1.5 x 1.1 inches (41 x 39 x 29 mm) across the flats
and 2
.48 x 2 inches (63 x 50 mm) across the diagonals
This specimen weighs 4
.58oz  or 0.28 lb (129g)
A Grade 26g Lavender Optical Calcite from Madagascar
We were able to procure a few special specimens in our never ending search for
quality Optical Calcites when we found this Optical Calcite Crystal from the
Mahajanga Province in Madagascar. We have sold many Optical Calcite
Crystals over the years from Mexico, Brazil and Germany. The most interesting
ones we have found in a long time have been these natural clear crystal rhombs
with a beautiful light Lavender or Lilac colored tint from Madagascar. They have
high quality clarity with excellent Birefringence. An excellent collection addition!
This specimen is SW and MW fluorescent (shown under MW Ultra Violet lamp)
measures 0.98 x 0.75 x 0.73" (25 x 19 x 18mm) or 1.46 x 1.23" (37 x 31mm) across the diagonals
This specimen weighs 0.9oz (26g)
Item # 3-MOPTCAL09186010
23g Optical Calcite Rhomb from Mexico
$8.00
Item # 5-MOPTCAL09186010
19g Optical Calcite Rhomb from Mexico
$7.00
1.87 x 1.55 x 0.32" (47.5 x 39.5 x 8.2mm)
1.61 x 1.35 x 0.47" (41 x 34.3 x 12.1mm)
Item #14-MLAVOCL08195931
26g Lavender Optical Calcite
Rhomb from Madagascar

$28.00
A Grade 81.5g Lavender Optical Calcite from Madagascar
We were able to procure a few special specimens in our never ending search for
quality Optical Calcites when we found this Optical Calcite Crystal from the
Mahajanga Province in Madagascar. We have sold many Optical Calcite
Crystals over the years from Mexico, Brazil and Germany. The most interesting
ones we have found in a long time have been these natural clear crystal rhombs
with a beautiful light Lavender or Lilac colored tint from Madagascar. They have
high quality clarity with excellent Birefringence. An excellent collection addition!
measures 1.8 x 1.3 x 0.73" (47 x 33 x 18.5mm) or 2.6 x 2.2" (67 x 56mm) across the diagonals
This specimen weighs 2.8oz  or 0.18 lb (81.5g)
Item #7-MLAVOCL03199941
81.5g Lavender Optical Calcite
Rhomb from Madagascar

$48.90
<--- Fluorescence and birefringence of 445 nm
laser in optical calcite crystal
https://commons.wikimedia.org/wiki/File:Fluorescence_in_calcite.jpg
A Grade 92g Lavender Optical Calcite from Madagascar
We were able to procure a few special specimens in our never ending search for
quality Optical Calcites when we found this Optical Calcite Crystal from the
Mahajanga Province in Madagascar. We have sold many Optical Calcite
Crystals over the years from Mexico, Brazil and Germany. The most interesting
ones we have found in a long time have been these natural clear crystal rhombs
with a beautiful light Lavender or Lilac colored tint from Madagascar. They have
high quality clarity with excellent Birefringence. An excellent collection addition!
measures 1.8 x 1.3 x 0.82" (47 x 33 x 20.8mm) or 2.6 x 2.1" (67 x 54mm) across the diagonals
This specimen weighs 3.2oz  or 0.20 lb (92g)
Item #10-MLAVOCL03198941
92g Lavender Optical Calcite
Rhomb from Madagascar

$38.64
A Grade 179g Lavender Optical Calcite from Madagascar
We were able to procure a few special specimens in our never ending search for
quality Optical Calcites when we found this Optical Calcite Crystal from the
Mahajanga Province in Madagascar. We have sold many Optical Calcite
Crystals over the years from Mexico, Brazil and Germany. The most interesting
ones we have found in a long time have been these natural clear crystal rhombs
with a beautiful light Lavender or Lilac colored tint from Madagascar. They have
high quality clarity with excellent Birefringence. An excellent collection addition!
This specimen is SW and MW fluorescent (shown under MW Ultra Violet lamp)
measures 2.3 x 1.5 x 1" (58 x 40 x 26mm) or 3.2 x 2.7" (81 x 68mm) across the diagonals
This specimen weighs 6.32oz or 0.4 lb (179g)
Item #15-MLAVOCL08190013
179g Lavender Optical Calcite
Rhomb from Madagascar

$69.00
A Grade 192g Lavender Optical Calcite from Madagascar
We were able to procure a few special specimens in our never ending search for
quality Optical Calcites when we found this Optical Calcite Crystal from the
Mahajanga Province in Madagascar. We have sold many Optical Calcite
Crystals over the years from Mexico, Brazil and Germany. The most interesting
ones we have found in a long time have been these natural clear crystal rhombs
with a beautiful light Lavender or Lilac colored tint from Madagascar. They have
high quality clarity with excellent Birefringence. An excellent collection addition!
This specimen is SW and MW fluorescent (shown under MW Ultra Violet lamp)
measures 1.9 x 1.7 x 1.2" (4.9 x 4.2 x 3.1 cm) or 2.9 x 2.3" (7.5 x 5.9 cm) across the diagonals
This specimen weighs 6.78oz or 0.42 lb (192g)
Item #20-MLAVOCL12191022
192g Lavender Optical Calcite
Rhomb from Madagascar

$69.00
A Grade 154g Lavender Optical Calcite from Madagascar
We were able to procure this specimen in our never ending search for quality
Optical Calcites when we found this Optical Calcite Crystal from the Mahajanga
Province in Madagascar. The most interesting ones we have found in a long time
have been these natural clear crystal rhombs with a beautiful light Lavender or
Lilac colored tint from Madagascar. It has excellent birefringance and some
rainbow. This specimen is SW and MW fluorescent (shown under MW Ultra
Violet lamp)
measures 2.88 x 1.5 x 0.8" (7.3 x 3.8 x 2cm) or 3.6 x 3" (9.2 x 7.8cm) across the diagonals
This specimen weighs 5.4oz or 0.34 lb (154g)
Item #17-MLAVOCL12192022
154g Lavender Optical Calcite
Rhomb from Madagascar

$64.00
Item # 19-BOPTCAL12191151
70g A Grade Polished Optical
Calcite from Brazil

$57.00
A Grade 70g Clear Polished Optical Calcite from Brazil
We were able to procure a few special specimens in our never ending search
for quality Optical Calcites when we found this Optical Calcite Crystal from
Mato Grosso do Sol, Brazil that was ground and polished.  We have sold many
Optical Calcite Crystals over the years from Mexico, Germany, Madagascar
and Brazil. The most popular so far have been the Brazilian crystals that are
polished with beveled edges. This Optical Calcite has good clarity with
excellent Birefringence.

This specimen measures 1.45 x 1.12 x 0.9 inches (37 x 28.5 x 23mm) across the flats and
2 x 1.65 inches (52 x 42 mm) across the diagonals and weighs 2.46oz  or 0.155 lb (70g)
Item # 21-GBOPTCAL12195095
107g A Grade Optical Calcite
from Brazil Polished in
Idar-Oberstein

$1
32.00
A Grade 107g Clear Optical Calcite from Brazil, Polished in Idar-Oberstein

We were able to procure a few special specimens in our never ending search for
quality Optical Calcites when we found this Optical Calcite Crystal from Mato
Grosso do Sol, Brazil that was ground and polished in Idar-Oberstein, Germany
(Deutchland).  We have sold many Optical Calcite Crystals over the years from
Mexico, Germany, Madagascar and Brazil. The most popular so far have been
the Brazilian crystals that are polished with beveled edges.  The best of these
Brazilian Calcites are the ones ground and polished by the artisans in
Idar-Oberstein. Of all Optical Calcites we have ever come across, these
Idar-Oberstein calcites are hands down the highest quality clarity with excellent
Birefringence.

This specimen is a beautiful specimen of Idar-Oberstein polished
Brazilian Optical Calcite.

This specimen measures 1.5 x 1.4 x 1 inches (39 x 34 x 27 mm) across the flats
and 2
.3 x 1.8 inches (58 x 47 mm) across the diagonals
This specimen weighs 3
.74oz  or 0.23 lb (107g)