|
INVESTIGATIONS
Stone |
RI min |
RI max |
Dens min |
Dens max |
Colour |
Location |
Info |
Spectrum |
UVS |
UVL |
Reference |
Opal |
1,36 |
1,44 |
1,74 |
1,89 |
play of colour with
typically white bodycolour, some brown, fire and colourless |
Wegel Tena, Wollo
Province, Ethiopia |
opaque to translucent,
become transparent when soaked in water, "digit patterns"; chelsea:
orange to bright red; black opaque xx (pyrite?) |
|
inert to strong (weaker
than UVL): bluish white, yellow, green |
inert to strong: bluish
white, yellow, green |
Gems & Gemology 2010
Summer, p90-105 |
Opal |
1,36 |
1,43 |
2 |
2 |
white, fire (red, orange,
yellow), water-opal |
Mexico |
hardness litlle less than
6, somewhat lower than that of Australian opals, due to the greater
water-content |
|
|
|
The Australian
Gemmologist 1986 |
Opal |
1,37 |
1,41 |
1,7 |
1,77 |
purple (dyed) |
probably : Wollo,
Ethiopia |
dyed hydrophane |
|
|
|
Gems & Gemology 2011
Winter, p260-270 |
Opal |
1,4 |
1,45 |
1,35 |
2,03 |
near colourless, milky
white, yellow, orange, brown (good play of colours to weak) |
Yita Ridge, Shewa (Showa)
Province, Ethiopia |
transparent to opaque;
some brown stones appeared red |
|
inert, faint to strong
yellow-green, faint blue-white, blue, orange |
inert, faint to weak
yellow-green, blue, yellow, orange |
Gems & Gemology 1996
summer, p112-120 |
Opal |
1,4 |
1,44 |
1,99 |
2,01 |
colourless, yellow,
brownish orange |
Laverton, Western
Australia |
0.49-4.39ct, common opal |
|
colourless: strong white |
|
Gems & Gemology 2011
Winter, p318-319 |
Fire opal |
1,415 |
1,46 |
2,05 |
2,26 |
yellow, orange, red (no
play of colour) |
Bemia, Madagascar |
|
|
|
inert to moderate
yellow-green |
Gems & Gemology 2010
Summer, p114-121 |
Opal |
1,42 |
1,445 |
1,92 |
2,08 |
green, yellow |
Mali |
|
|
|
|
Extra Lapis Nr 10 Opal
1996 p22 |
Opal |
1,42 |
1,43 |
1,95 |
2,05 |
reddish orange with colour play (predominantly green and
red) |
Queretaro, Mexico |
often high degree of transparency |
|
|
|
Gems & Gemology 1983
summer, p87-96 |
Opal |
1,42 |
1,43 |
2,11 |
2,12 |
|
Andamooka, Australia |
treated matrix |
|
|
|
The Australian
Gemmologist 2003 Vol 21,N°11, p446 |
Opal |
1,42 |
1,43 |
|
|
intense hues of red, blue
and green |
Queensland, Australia |
"boulder opal"
: gem quality opal that retains some portion of the ironstone matrix when cut |
|
|
|
Gems & Gemology 1993
spring, p4-15 |
Opal |
1,42 |
1,47 |
1,3 |
2,2 |
hyalite, rainbow opal,
fire opal, play-of-color varieties : contra luz, hydrophone, crystal opal |
Opal Butte, Oregon, USA |
hydrophane: density 1.3 |
|
|
|
Gems & Gemology 1988
Winter, p229-236 |
Opal |
1,42 |
1,42 |
2,02 |
2,02 |
multicoloured, play of
colour |
Mexico |
6.05ct, spot RI |
no features |
inert |
inert |
GIA Gem Database 33367 |
Opal |
1,42 |
1,42 |
2,12 |
2,12 |
orange |
Shikaribetsu Lake area in
Kato District, Tokachi Province, Hokkaido, Japan |
cabochon, 2.20ct, RI spot |
|
|
strong orange |
The Journal of Gemmology
2018 36(4), p287 |
Opal |
1,422 |
1,44 |
1,98 |
2,02 |
|
Tintenbar, Australia |
|
|
|
|
The Australian
Gemmologist 2003 Vol 21,N°11, p446 |
Opal |
1,43 |
1,45 |
1,96 |
2,04 |
white, brown, dark brown,
black |
Java, Indonesia |
|
|
inert to very faint
chalky blue |
inert to faint chalky
blue |
The Australian
Gemmologist 2009 23, 513-528 |
Opal |
1,43 |
1,452 |
2,01 |
2,08 |
blue |
Acari, Nazca, Peru |
hardness 5 |
|
inert |
inert |
The Journal of Gemmology
2001 Vol 27, N°6, p328-329 |
Opal |
1,43 |
1,51 |
2,04 |
2,43 |
blue, pink, green |
Acari, Nazca, Peru |
translucent -> opaque |
|
strong greenish yellow
areas |
|
The Australian Gemmologist
2007 Vol 23, N°1, p3-15 |
Opal |
1,43 |
1,43 |
2,03 |
2,03 |
light to dark yellowish
green with dendritic black inclusions |
Brazil |
translucent cabochons,
0.99, 2.22, and 1.84 ct, spot RI |
|
inert |
inert |
Gems & Gemology 1986
p110 |
Opal |
1,43 |
1,44 |
2,08 |
2,08 |
white-to-grey areas,
alternated with purple to orangey red bands, as well as pink and
‘mustard’-yellow layers |
Utah, USA |
Utah Lace Opal, cabochons
44.63ct and 29.67ct; RI spot, opaque |
|
|
|
The Journal of Gemmology
2016 35 (4), p 282 |
Fire opal |
1,431 |
1,431 |
2,05 |
2,05 |
orange |
Opal Butte, Oregon, USA |
|
|
|
|
Gemmologie, Zeitschrift
der Deutschen Gemmologischen Gesellschaft 1997 Sep, p161-168 |
Opal |
1,435 |
1,468 |
1,98 |
2,06 |
colourless (water-opal),
brown (tea-opal), grey, black |
Java (Rangkasbitung,
Banten Province) |
|
|
inert |
inert |
The Journal of Gemmology
2007 Nr 7/8, p383-397 |
Opal |
1,435 |
1,468 |
1,98 |
2,06 |
with play-of-colour:
white (milky to white), black (blackish brown); fire opal: yellowish
reddish; colourless; without play:
colourless, greenish, yellowish, brown |
Java, Indonesia |
|
|
|
|
The Australian
Gemmologist 2005 Vol 22, N°6, p254-259 |
Opal |
1,435 |
1,468 |
1,98 |
2,06 |
|
Java, Indonesia |
|
|
|
|
Gemmologie, Zeitschrift
der Deutschen Gemmologischen Gesellschaft 2004 |
Opal |
1,438 |
1,442 |
2,03 |
2,06 |
green |
Turkey |
Cr³+ chromophore |
two broad bands at 599
and 370nm, sharp line at 681nm |
|
|
Gemmologie, Zeitschrift
der Deutschen Gemmologischen Gesellschaft 1997 Mar, p2 |
Fire opal |
1,439 |
1,447 |
1,98 |
2 |
orange-red, play of
colour |
Ethiopia |
|
cut-off at 600nm |
|
|
Gemmologie, Zeitschrift
der Deutschen Gemmologischen Gesellschaft 1997 Mar, p4 |
Fire opal |
1,439 |
1,441 |
1,99 |
2,03 |
orange-red to fire-red |
Campos Borges, Rio Grande
do Sul, Brazil |
2.95, 3.64, 7.33 ct |
|
|
|
Gemmologie, Zeitschrift
der Deutschen Gemmologischen Gesellschaft 1995 Sep, p43-46 |
Fire opal |
1,439 |
1,441 |
2 |
2,02 |
orange, yellow |
Rio Grande do Sul, Brazil |
|
|
|
|
http://www.dgemg.com/
2021 3 |
Opal |
1,44 |
1,45 |
1,98 |
2,05 |
black matrix (after
treatment) |
Andamooka, Australia |
hardness 6 |
|
|
blue-white |
Gems & Gemology 1991
Summer, p100-106 |
Opal |
1,44 |
1,453 |
2,09 |
2,13 |
black |
Lightning Ridge,
Australia |
|
|
|
|
The Australian
Gemmologist 2003 Vol 21,N°11, p446 |
Opal |
1,44 |
1,46 |
2,11 |
2,13 |
light |
Andamooka, Australia |
|
|
|
|
The Australian
Gemmologist 2003 Vol 21,N°11, p446 |
Opal |
1,44 |
1,44 |
2,14 |
2,14 |
greenish blue to blue,
turquoise |
Andes Mts, Peru |
translucent |
|
|
|
Gemmologie, Zeitschrift
der Deutschen Gemmologischen Gesellschaft 1995 Mar, p5 |
Opal |
1,44 |
1,44 |
2,18 |
2,18 |
purple |
Mexico |
common opal, coloured by
fluorite inclusions, trade name: opal royale |
|
very strong green |
weak green |
Gems & Gemology 2012
Spring, p56 |
Opal |
1,44 |
1,48 |
2,14 |
2,14 |
yellow |
West Africa |
transparent to
translucent |
|
inert |
inert |
Gems & Gemology 2012
Fall, p226-227 |
Fire opal |
1,44 |
1,44 |
2,02 |
2,02 |
yellow |
Tuléar Province,
Madagascar |
1.72ct |
|
inert |
inert |
ACAM Lab 1833 |
Opal |
1,44 |
1,44 |
2,03 |
2,11 |
yellow, orange, brownish
orange, and orangy brown |
Tanzania |
4.04 - 6.71 ct, cabochon,
cats-eye, spot RI |
|
inert |
inert |
Gems & Gemology 1998
Summer, p137-138 |
Opal |
1,44 |
1,44 |
2,02 |
2,02 |
black (dark orange-brown
in intense transmitted light), play of colour in the form of chatoyant bands |
Jalisco, Mexico |
cabochon 2.16ct, spot RI |
|
|
|
Gems & Gemology 1990
Winter, p304 |
Opal |
1,44 |
1,445 |
2,02 |
2,04 |
yellow-green to orange |
Argentina |
4.26 - 8.06 ct,
cabochons, opaque to transparent |
|
inert |
inert to very weak
whitish green |
Gems & Gemology 2009
Fall, p220 |
Opal |
1,44 |
1,44 |
2,1 |
2,1 |
yellowish green to yellow |
Brazil |
cabochons 1.89-6.35ct, RI
spot, semi-transparent |
|
very weak red to orange |
very weak red to orange |
The Journal of Gemmology
2018 36(3) p188 |
Opal |
1,44 |
1,44 |
2,01 |
2,01 |
multicoloured, play of
colour |
Mexico |
6.59ct, spot RI |
no features |
inert |
inert |
GIA Gem Database 34464 |
Opal |
1,44 |
1,44 |
2,26 |
2,26 |
colourless with dark
brown dentrites |
Brazil |
11.85ct cabochon, spot RI |
|
strong yellowish green |
faint blue |
The Journal of Gemmology
2019 36 (6), p 504 |
Opal |
1,44 |
1,44 |
2,26 |
2,26 |
colourless with dark
brown dentrites |
Brazil |
11.85ct cabochon, spot RI |
|
strong yellowish green |
faint blue |
The Journal of Gemmology
2019 36 (6), p 504 |
Fire opal |
1,442 |
1,446 |
2 |
2,02 |
|
Shaphané Mts, Turkey |
0.73 ct , 1.27 ct |
|
|
|
Gemmologie, Zeitschrift
der Deutschen Gemmologischen Gesellschaft 1995 Mar, p5 |
Opal |
1,442 |
1,455 |
2,05 |
2,11 |
light |
Coober Pedy, Australia |
|
|
|
|
The Australian
Gemmologist 2003 Vol 21,N°11, p446 |
Opal |
1,445 |
1,445 |
2,11 |
2,11 |
greenish-yellow |
Sri Lanka |
cat's eye, 7.58ct |
|
|
|
Gemmologie, Zeitschrift
der Deutschen Gemmologischen Gesellschaft 1999 Mar, p3 |
Opal |
1,445 |
1,458 |
2,12 |
2,13 |
|
Lambina, Australia |
|
|
|
|
The Australian
Gemmologist 2003 Vol 21,N°11, p446 |
Opal |
1,446 |
1,448 |
2,13 |
2,15 |
turquoise blue |
Brazil |
translucent to
transparent, 1.53 to 4.90 ct |
|
|
|
Gemmologie, Zeitschrift
der Deutschen Gemmologischen Gesellschaft 1996 Dec, p155 |
Opal |
1,446 |
1,453 |
2,05 |
2,15 |
greenish yellow |
Nioro du Sahel, Kayes,
Mali |
2.74ct |
|
|
|
Gemmologie, Zeitschrift
der Deutschen Gemmologischen Gesellschaft 2013 62/1-2, Jun, p46-48 |
Fire opal |
1,448 |
1,448 |
2,06 |
2,06 |
orange, yellow |
Aleksejewskoje,
Kazakhstan |
|
|
|
|
Zeitschrift der Deutschen
Gemmologischen Gesellschaft 1991 Apr, p11-23 |
Opal |
1,449 |
1,452 |
2,06 |
2,11 |
colourless, with green
daylight fluorescence |
Erongo, Namibia |
hyalite, transparent |
|
|
|
The Journal of Gemmology
2022 38(2), p172-182 |
Opal |
1,45 |
1,47 |
2 |
2,06 |
blue-green, translucent |
110 km NW of Shahr-e
Babak, Kerman Province, Iran |
|
600nm cut-off |
inert |
inert |
Gems & Gemology 2007
fall p 257 |
Opal |
1,45 |
1,46 |
2,08 |
2,1 |
light |
White Cliffs, Australia |
|
|
|
|
The Australian
Gemmologist 2003 Vol 21,N°11, p446 |
Opal |
1,45 |
1,457 |
2,09 |
2,1 |
potch |
Lightning Ridge,
Australia |
|
|
|
|
The Australian
Gemmologist 2003 Vol 21,N°11, p446 |
Opal |
1,45 |
1,45 |
2,11 |
2,11 |
blue |
Lily Mine, Peru |
|
cutoff at around 650nm |
very weak bluish |
very weak bluish |
Gems & Gemology 2003
winter p 332 |
Opal |
1,45 |
1,456 |
2,11 |
2,13 |
|
Mintabie, Australia |
|
|
|
|
The Australian
Gemmologist 2003 Vol 21,N°11, p446 |
Opal |
1,45 |
1,49 |
2,16 |
2,22 |
pink |
Peru |
mixture of palygorskite,
opal and chalcedony, hardness 6 |
|
colourless veinlets :
bright green |
pinkish-white |
The Journal of Gemmology
2001 Vol 27, N°6, p328-329 |
Opal |
1,45 |
1,54 |
2,23 |
2,44 |
blue, light greyish blue
with play of colour |
Southern Skies Mine,
Arizona |
patterns of blue opal in
a mostly brown matrix, spot RI |
|
weak blue, yellow |
|
Gems & Gemology 2012
Fall, p226 |
Opal |
1,45 |
1,45 |
2,14 |
2,14 |
white |
Milford, Utah, USA |
37.18ct, cabochon,
botryoidal |
|
inert |
inert |
Gems & Gemology 1997
Spring, p63-64 |
Opal |
1,45 |
1,45 |
2,08 |
2,08 |
brownish yellow |
|
9.00 ct, cabochon,
cat's-eye |
|
weak red |
inert |
Gems & Gemology 1998
Spring, p44-45 |
Opal |
1,45 |
1,45 |
2,08 |
2,08 |
brownish yellow |
|
0.76ct cabochon,
cat's-eye, exhibits a strong "milk-and-honey" effect |
|
weak red |
weak red |
Gems & Gemology 1990
Fall,p230 |
Opal |
1,45 |
1,45 |
2,16 |
2,23 |
pink |
|
spot RI |
weak band at 490 nm, a
weak line at 550 nm, and a cutoff from 430 nm |
very |
weak-to-medium whitish |
Gems & Gemology 2004
Fall, p246 |
Opal |
1,45 |
1,47 |
2,01 |
2,01 |
greenish yellow |
Brazil |
2.76ct, cat's-eye |
general absorption up to
530 nm and weak bands at 620 nm and 670 nm |
inert |
dull yellow-green |
Gems & Gemology 1992
Fall, p194 |
Opal |
1,45 |
1,45 |
2,12 |
2,16 |
light to very light
yellow, green (caused by day-light fluorescence) |
Mexico |
0.83 - 1.81 ct, RI approximately 1.45, transparent (hyalite),
"electric opal" |
|
|
|
The Journal of Gemmology
2014 Vol 34, N°4, p 294-296 |
Opal |
1,45 |
1,46 |
2,12 |
2,16 |
green, transparent |
Zacatecas, Mexico |
green daylight
luminescing hyalite opal |
|
very strong green |
very strong green |
The Journal of Gemmology
2015 Vol 34, No.6, p486-488 |
Opal |
1,45 |
1,455 |
2,05 |
2,1 |
greenish-blue |
Peru |
transparent, dendritic
inclusions of manganese oxide |
|
|
|
Gemmologie, Zeitschrift
der Deutschen Gemmologischen Gesellschaft 2016 Jun, p5-6 |
Opal |
1,45 |
1,5 |
2,24 |
2,31 |
purple, mottled |
Utah, USA |
cabochon, opaque,
coloured by purple fluorite inclusions |
|
|
|
The Journal of Gemmology
2019 Vol 36, N°5, p404-407 |
Opal |
1,45 |
1,45 |
2,13 |
2,13 |
yellow green to dark
green |
Peru |
1,26ct and 1,76ct,
Cr-bearing, translucent, red under Chelsea filter |
|
weak yellow green |
yellow green |
The Journal of Gemmology
2022 38 (2), p120 |
Opal |
1,451 |
1,459 |
2,09 |
2,13 |
light to medium dark
bluish green, opaque to translucent |
Haneti, Tanzania |
prase opal |
broad absorption below
450 and above 650nm |
|
|
Gems & Gemology 2009
Winter, p271-279 |
Opal |
1,452 |
1,452 |
2,125 |
2,125 |
green (prase opal) |
Tanzania |
|
|
whitish areas : strong to
moderate , bluish white |
moderate to weak |
Gems & Gemology 1984
winter, p226-227 |
Opal |
1,455 |
1,455 |
2,18 |
2,18 |
yellowish green |
Mexico |
faceted, 2.30ct, slightly
radioactive (0.1 to 0.4mR/hr), |
|
extremely strong, bright,
yellowish green |
extremely strong, bright,
yellowish green |
Gems & Gemology 1985
Summer, p111 |
Opal |
1,458 |
1,458 |
2,08 |
2,011 |
|
Pedro II, Piaui, Brazil |
|
|
|
|
Gemmologie, Zeitschrift
der Deutschen Gemmologischen Gesellschaft 1997 Jun, p104 |
Opal |
1,459 |
1,459 |
2,15 |
2,15 |
yellowish to brownish
yellow with dendritic psilomelane inclusions |
Lake Kariba, Zambia |
dentritic opal |
|
moderate greenish-yellow |
moderate yellowish |
Zeitschrift der Deutschen
Gemmologischen Gesellschaft 1993 Dec, p137 |
Fire opal |
1,459 |
1,462 |
2,15 |
2,18 |
reddish brown-orange,
brownish orange, and brownish yellow |
Juniper Ridge, Oregon,
USA |
1.39 to 5.48 ct |
|
very weak chalky green |
inert |
Gems & Gemology 2003
Spring, p55-56 |
Opal |
1,46 |
1,46 |
2,15 |
2,15 |
yellow-green |
Tsivory, Madagascar |
|
|
|
|
Gemmologie, Zeitschrift
der Deutschen Gemmologischen Gesellschaft 2000 Juni, p85-94 |
Opal |
1,46 |
1,47 |
2,32 |
2,32 |
blue with play-of-colour |
Cosala, Sinaloa, Mexico |
"lightning blue
opal" |
|
strong green |
inert |
Gems & Gemology 2011
Fall, p243 |
Opal |
1,46 |
1,46 |
2,1 |
2,1 |
pale, slightly bluish
green |
Serbia |
cabochon, 21.08ct |
cut-off edges at 450 and
620 nm |
inert |
faint chalky green |
Gems & Gemology 1995
Fall, p208 |
Opal |
1,46 |
1,47 |
2,1 |
2,13 |
light green |
Serbia ? |
5.36 - 17.74ct,
cabochons, semi-translucent to translucent |
general absorption below
450 nm and above 620nm |
very weak green |
weak green |
Gems & Gemology 2007
Summer, p171 |
Opal |
1,46 |
1,46 |
2,16 |
2,16 |
yellow-green in sunlight,
strong yellow in artificial light |
Mexico |
1.25ct, hyalite |
|
|
|
https://www.dgemg.com/newsletter/gemmologie-aktuell
2015 13th august |
Opal |
1,46 |
1,47 |
2,24 |
2,28 |
blue |
Rio Grande do Sul, Brazil |
|
|
|
|
http://www.dgemg.com/
2021 3 |
Opal |
1,462 |
1,467 |
2,241 |
2,27 |
light brown, iridescent
effect |
San Luis Potosi, Mexico |
hyalite, "iris
opal", transparent |
|
|
|
Zeitschrift der Deutschen
Gemmologischen Gesellschaft 1989 Aug, p51-62 |
Opal |
1,47 |
1,47 |
2,14 |
2,18 |
yellowish green to
yellowish brown |
Brazil |
cat's-eye (parallel
aranged fibres of chrysotile) |
|
|
|
Gemmologie, Zeitschrift
der Deutschen Gemmologischen Gesellschaft 1996 Mar, p3 |
Opal |
1,475 |
1,475 |
2,18 |
2,25 |
pink, opaque, cause of
colour : organic compounds called quinones |
Monte Rosa, Peru |
mixture of opal with
palygorskite, H : 6 |
|
inert |
weak pinkish white |
Gems & Gemology 2006
summer, p176 |
Opal |
1,495 |
1,495 |
2,2 |
2,35 |
|
Grale of God Mine, Sierra
Madre Mts, Sonora, Mexico |
|
|
|
|
Gemmologie, Zeitschrift
der Deutschen Gemmologischen Gesellschaft 1995 Mar, p5 |
Opal |
|
|
1,4 |
2 |
white |
Oman |
Cascholong opal , hardness
3 - 6 |
|
|
|
Zeitschrift der Deutschen
Gemmologischen Gesellschaft 1993 Dec, p141-148 |
Opal |
|
|
1,65 |
1,9 |
white, play of colour |
Wegel Tena, Wollo
Province, Ethiopia |
7-12 ct, high porosity |
|
|
|
Gemmologie, Zeitschrift
der Deutschen Gemmologischen Gesellschaft 2010 59/3-4, p65 |
Opal |
|
|
1,91 |
2,37 |
pink, green, pale blue,
yellowish green, ochre |
Acari, Nazca, Peru |
opal-C, opal-CT &
opal-T |
|
|
|
The Australian
Gemmologist 2008 Vol 23,N°6, p266-271 |
Opal |
|
|
2,08 |
2,1 |
apple green, translucent |
border area
Croatia-Macedonia |
|
bands in the red and
violet (due to Ni) |
|
|
Gemmologie, Zeitschrift
der Deutschen Gemmologischen Gesellschaft 2003 Dec, p123 |
TABLES
Stone |
RI
min |
RI
max |
Dens
min |
Dens
max |
Reference |
Opal |
1.37 |
1.47 |
1.25 |
2.35 |
Bestimmungstabellen für Edelsteine,
Birgit Günther, 2008 |
Opal |
1.37 |
1.47 |
1.25 |
2.25 |
Gemme, Dati per l'identificazione, P. De
Stefano et al, 1993 |
Opal |
1.37 |
1.47 |
1.97 |
2.22 |
Gemmological Tables, Ulrich Henn,
2004 |
Opal |
1.37 |
1.47 |
1.99 |
2.25 |
http://www.gemmology.be |
Opal |
1.37 |
1.47 |
2.05 |
2.25 |
Tabellen zur Edelstein-Bestimmung,
Pschichholz FGA, 1975 |
Opal |
1.37 |
1.47 |
1.99 |
2.25 |
Joel Arem, Color
Encyclopedia of Gemstones, 1987 |
Opal |
1.37 |
1.475 |
1.95 |
2.25 |
Tables of
Gemstone Identification, Roger Dedeyne, Ivo Quintens, 2007 |
Opal |
1.37 |
1.47 |
1.25 |
2.23 |
Gemology Tools Professional 2010 |
Fire opal |
1.38 |
1.47 |
1.25 |
2.23 |
Gemology Tools Professional 2010 |
Opal |
1.38 |
1.47 |
1.3 |
2.3 |
Gemmo.eu
|
Fire opal |
1.435 |
1.445 |
1.97 |
2.06 |
John Sinkakas,
Gemstone and mineral data book,1972 |
Fire opal |
1.435 |
1.455 |
1.97 |
2.06 |
Gems, R Webster,
5th edition 1994 |
Fire opal |
1.44 |
1.446 |
2 |
2.15 |
Tables of
Gemstone Identification, Roger Dedeyne, Ivo Quintens, 2007 |
Opal |
1.44 |
1.46 |
1.95 |
2.2 |
John Sinkakas,
Gemstone and mineral data book,1972 |
Opal |
1.44 |
1.47 |
1.97 |
2.5 |
http://www.geminterest.com |
Opal |
1.44 |
1.46 |
1.98 |
2.2 |
Gems, R Webster,
5th edition 1994 |
CAUSE OF
COLOUR
Stone |
Colour |
Cause
of colour |
Reference |
Opal |
blue, greenish blue, green |
Cu²+ in form of
submicroscopic inclusions |
The Australian Gemmologist, 2007,
Vol23,N°1,p14 |
Opal |
green |
Cr³+ |
Gemmologie, 1997 Dez, p2-3 |
Opal |
green (prase opal) |
microscopic to
submicroscopic inclusions of nickeliferous clay like inclusions |
Gems & Gemology Summer 1988 |
Opal |
multicolours |
diffraction by
the regular stacking of silica spheres |
Gems & Gemology Summer 1988 |
fire opal |
orange to red |
microscopic to
submicroscopic inclusions of iron hydrous oxides |
Gems & Gemology Summer 1988 |
Opal |
pink |
organic compounds, called quinones |
Gems & Gemology Summer 2006, p176 |
Opal |
pink |
inclusions of cinnabar |
Rondeau B. (1998) Origine de la couleur
et structure des opales communes, Université de Nantes |
Opal |
purple |
fluorite inclusions |
Gems & Gemology Spring 2012, p56-57 |
Opal |
yellow |
microscopic inclusions of orpiment |
Rondeau B. (1998) Origine de la couleur
et structure des opales communes, Université de Nantes |
MINERAL
INCLUSIONS
Inclusion |
Stone |
Reference |
anatase |
Opal |
Gems & Gemology 2012,
Fall, p226 |
aragonite |
Opal |
Gems & Gemology 2017
Winter, p466 |
barite |
Opal |
E.J. Gübelin and J.I.
Koivula, Photoatlas of inclusions in Gemstones, volume 2 (2005) |
chabazite |
Opal |
Gems & Gemology 2020
Summer, p293 |
chalcedony |
Opal |
Gemmological Tables,
Ulrich Henn , GGA, 2004 |
chromite |
Opal |
Gems & Gemology 2020
Winter, p521 |
cinnabar |
Opal |
The Journal of Gemmology
2022, 38(3) p217-218 |
cristobalite |
Opal |
E.J. Gübelin and J.I.
Koivula, Photoatlas of inclusions in Gemstones, volume 2 (2005) |
cristobalite |
fire opal |
Gemmologie, Sep 1997,p167 |
fluorite |
Opal |
Gems & Gemology 1983
Summer p94 |
goethite |
Opal |
Gemmological Tables,
Ulrich Henn , GGA, 2004 |
hematite |
fire opal |
E.J. Gübelin and J.I.
Koivula, Photoatlas of inclusions in Gemstones, volume 2 (2005) |
hornblende |
Opal |
The Australian
Gemmologist, 1986, Vol 16,Nb 2, p49 |
kaolinite |
Opal |
E.J. Gübelin and J.I.
Koivula, Photoatlas of inclusions in Gemstones, volume 2 (2005) |
pyrite |
Opal |
E.J. Gübelin and J.I.
Koivula, Photoatlas of inclusions in Gemstones, volume 2 (2005) |
quartz |
Opal |
Gems & Gemology 1983
Summer p94 |
zeolite |
Opal |
Gems & Gemology 2011
Winter, p266 |
LOCALITIES
STONE |
LOCALITIES |
REFERENCE |
|||
Opal |
Lightning Ridge |
New England District |
New South Wales |
Australia |
Gems & Gemology Fall 2010, p211 |
Opal |
|
White Cliffs |
New South Wales |
Australia |
Gems & Gemology Fall 2010, p211 |
Opal |
Yowah opal field |
Eulo (87km) |
Queensland |
Australia |
Lapis 5/1990 |
Opal |
|
Opalton |
Queensland |
Australia |
Gems & Gemology Fall 2010, p211 |
Opal |
|
Quilpie |
Queensland |
Australia |
Le Règne minéral 26/1999 |
Opal |
Stuart Creek Opal Diggings, Stuart Creek |
Andamooka Ranges
- Lake Torrens area |
South Australia |
Australia |
Gems & Gemology Fall 2010, p211 |
Opal |
Coober Pedy |
Coober Pedy |
South Australia |
Australia |
Noble, R.J. (1983) |
Opal |
Mintabie opal field |
Coober Pedy -
Everard Range Regions |
South Australia |
Australia |
Gems & Gemology Fall 2010, p211 |
Opal |
|
Lambina |
South Australia |
Australia |
Gems & Gemology 2004 Fall p276 |
Opal |
|
Mintabie |
South Australia |
Australia |
Gems & Gemology Fall 2010, p211 |
Opal |
Boi Morto Mine
(Mina do Boi Morto), Pedro II |
Piaui |
|
Brazil |
Gems & Gemology 2002 Fall p268 |
Opal |
Manoel Ambrosio Ranch |
Sao Geraldo do Araguaia |
Minas Gerais |
Brazil |
Revista Brasileira de Geociências,
vol.30 |
Opal |
Klinker prospect, Vernon |
Vernon Mining Division |
British Columbia |
Canada |
Gems & Gemology Fall 2010, p211 |
Opal |
Tsehay Mewcha, Wegeltena, Delanta |
Welo (Wello; Wollo) |
Afar |
Ethiopia |
Gems & Gemology Summer 2010, p90-105 |
Opal |
Yita ridge |
Mezezo (Mezzezo) |
Showa Province |
Ethiopia |
Gem Information,
23 May 2007 (Japan Germany Gemmological Laboratory), 20-24. |
Opal |
|
|
Welo |
Ethiopia |
Gems & Gemology Spring 2009, p59-60 |
Opal |
|
Gracias |
Lempira Department |
Honduras |
N. Jb. Mineral. Abh. 186 (2009) 11-20. |
Opal |
Kali Maya |
Banteen Province |
Java |
Indonesia |
Extra Lapis -
English No. 10 Opal |
Opal |
|
110km NW of
Sharh-e Babak |
Kerman Province |
Iran |
Gems & Gemology 2007 fall, p257 |
fire opal |
|
Aleksejewskoje |
|
Kazachstan |
Zeitschrift der Deutschen Gemmologischen
Gesellschaft, 1991, Apr p11-23 |
fire opal |
Bemia |
Befotaka |
Fianarantsoa Province |
Madagascar |
Gems & Gemology 2010 Summer,
p114-121 |
fire opal |
|
Beraketa |
Tuléar (Toliara ) Province |
Madagascar |
Gemmologie, Dez 1999,p196 |
Opal |
|
Nioro du Sahel |
Kayes Region |
Mali |
Gemmologie, Zeitschrift der Deutschen
Gemmologischen Gesellschaft 2013 62/1-2, Jun, p46-48 |
Opal |
Leopard opal
deposit, 14km South of Zimapan |
Zimapan |
Hidalgo |
Mexico |
Gems & Gemology 2006 Winter p 238 |
Opal |
|
Cosala |
Sinaloa |
Mexico |
Gems & Gemology 2011, Fall, p243 |
Opal |
Monte Rosa Mine |
Ica Department |
|
Peru |
Extra Lapis -
English No. 10 Opal |
Opal |
Acari mine |
Nazca |
Arequipa Department |
Peru |
Hyrsl & Rosales (2003), Min. Record
34:254 |
Opal |
|
Hanety Hill (Haneti) |
|
Tanzania |
Gems & Gemology 2009 Winter, p271 |
Opal |
|
Claiborne County |
Mississippi |
USA |
Journal of the
Mississippi Academy of Sciences, Jan. 2004. |
Opal |
Virgin Valley District |
Humboldt County |
Nevada |
USA |
Minerals of
Nevada, Stephen B. Castor and Gregory C. Ferdock, 2004 |
fire opal |
Juniper Ridge Opal Mine |
Lake County |
Oregon |
USA |
Extra Lapis -
English No. 10 Opal |
Opal |
Opal Butte |
Morrow County |
Oregon |
USA |
Gems & Gemology 1988 winter |
CHEMICAL DATA
(%)
Stone |
Colour |
Locality |
Reference |
SiO2 |
Al2O3 |
MgO |
TiO2 |
CaO |
Na2O |
Fe2O3 |
K2O |
Cs2O |
H2O |
|
Opal |
blue |
|
|
The Journal of
Gemmology 2000, Vol 27, N°5,p282 |
98.71 |
0.1 |
0.03 |
0.01 |
0.33 |
0.73 |
|
0.09 |
|
|
Opal |
yellowish green |
|
Madagascar |
Gemmologie, Zeitschrift der deutschen
gemmologischen Gesellschaft, 2000, Jun, p89 |
92.79 |
2.06 |
0.1 |
|
0.18 |
0.06 |
0.5 |
0.1 |
|
3.5 |
Opal |
yellowish green |
|
Madagascar |
Gemmologie, Zeitschrift der deutschen
gemmologischen Gesellschaft, 2000, Jun, p89 |
94.1 |
1.02 |
|
|
0.12 |
|
0.25 |
|
|
3.5 |
Opal, hyalite |
light brown |
San Luis Potosi |
Mexico |
Zeitschrift der Deutschen Gemmologischen
Gesellschaft, 1989, Aug, p51-62 |
87.9 |
3.64 |
|
|
|
0.55 |
|
1.93 |
2 |
|