Opal Research

 

The following references summarise research and technical papers over the past 40 years. The list was originally prepared by the Editor of the Australian Gemmologist, Grahame Brown, with subsequent updating since 2000 by Anthony Smallwood. Back issues of the Australian Gemmologist can be purchased from their website at www.austgem.gil.com.au .
This page is divided in to the following Sections. Click to go directly to each:

1. Opal Papers in the Australian Gemmologist

2. Other References

2.1 Classification and evaluation of opal
2.1 Synthetic opal
2.3 Synthetic imitation opal
2.4 Natural imitation opal
2.5 Treated opal

3. Scientific References

4. References to opal in other mineral papers

 


1. OPAL PAPERS IN THE AUSTRALIAN GEMMOLOGIST

Extracted from the original Australian Gemmologist summary of articles: Australian Gemmologist April - June 2000 Volume 20 Number 10 p416, G Brown Editor.
 

updates by Anthony Smallwood, 2000-2005

Issue

Page/s

Title

Author

August, 1958

16

Andamooka field excursion

R. Harvey

December 1958

15

New discovery in Western Australia

P. McN

May 1959

16-17

Some notes on a recent West Australian mineral discovery

D.R. Walter

May 1959

22

Birth of the opal

Anon

July 1959

15-16

The Japanese opal market

R.B. Stokes

May 1960

 

 

5

Black opal

L. Hudson

7-16

Opal deposits and the Hayricks opal mine, Quilpie

H.G.S. Cribb

July 1960

6-7

The noble opal of Australia

A.A. Wirth

Nov-Dec 1960

12-15

Opal in the Eulo District

R.R. Dowding

December 1961

15-17

Gemstones of Australia

R.O.Chalmers

March 1962

13-14

The opal market

J.D. Altmann

June 1962

9-19

Microstructures in opal potch from Andamooka

Anon

February 1963

14-15

Research on opal

F. Lechman

July 1963

8-9

Hungarian opal

O’Mate

January 1964

9

An unusual colour pattern in precious opal from Andamooka

P.A. Males

February 1964

 

10-11

Relics from the past

F. Dowding

11

The miners of Koroit (poem)

R. Doeding

September 1964

9-10

Jasper-opal associated with diatomite from Cooma, NSW

P.A. Males

November 1964

7-8

Quartz matrix opal

P.Darragh & Gaskin

January 1965

11

The opal: Gem of mystery

Anon

February 1965

10-11

Matrix opal, Andamooka, South Australia

P.A. Males

April, 1965

9-12

The origin of colour in opal

P.J. Darragh &

J.V. Sanders

May 1965

13-14

Synthetic opals search

The Sun Herald

June 1965

5-8

The geology of Australian gemstone deposits

J.C. Liddy

January 1966

5-7

The geological environment of Australian opal

P.A. Males

March 1966

12-13

Boulders of opal

L.G. Cram

May 1966

11

A living opal

M.F. Day

June 1966

4

Restrictions on buying opal

A. H. Stevenson (Editor)

October 1966

10-13

Opal pseudomorphs and the candle-box trade

F.E. Murphy (Chapter from: They struck opal)

December 1966

 

 

5-9

The nature and origin of opal

P.J. Darragh, A.J. Gaskin  & J.V. Sanders

19-21

Go to Andamooka

G. Woods

January 1967

 

5-7

Iris opal from Mexico

J. Sinkankas

8

Opalised ‘steel band’ from Lightning Ridge

P.A. Males

June 1967

13

Opal geology

J.H. Oughton

November 1967

18

Phosphorescence in Australian opal

P.A. Males

February 1968

24-26

Precious opal in an unusual environment

P.A. Males

August 1968

27-28

Mexican fire opal

P.A. Males

November 1968

9-11

Opal in volcanic rock

P.A. Males

May 1969

10-13

A new occurrence of precious opal of volcanic origin near Mullimbimby, New South Wales

R.O. Chalmers

13-14

The first discovery of Australian opal

N. Clayton

November 1969

5-8

Volcanic gem opals: The results of an examination by electron microscopy

P.J. Darragh &

J.V. Sanders

February 1970

23

Opal story

W. Gower

May 1970

7-11

Opal in the nickel search in Western  Australia

R.T. Prider

May 1971

 

 

 

 

24

The classification of black opal

NSW Opal Research Group

24-26

Some thoughts on opal

Editorial Committee

26

Definition of black opal

Altman & Cherny

27

Myth of the Geierstein opal

P.B. Lapworth

August 1971

21-25

A scanning microscope study of the morphology of opal

E.R. Segnit,

C.A. Anderson &

J.B. Jones

November 1971

 

16

Black opal nomenclature

A. Kalokerinos

27-28

Spotted matrix opal

P.A. Males

February 1972

23-24

Opal nomenclature discussion

P.A. Males

August 1972

17-18

Lightning Ridge nobbies’ and the ‘Chainman’s hat’

P.A. Males

February 1973

15-16

Inclusions in opal

P.A. Males

August 1973

 

 

17-21

Precious opal – Developments towards synthesis

P.J. Darragh &

J.L. Perdrix

31

Opal classification – Your problem

J.H. Oughton (Editor)

November 1973

16-19

Scanning electron microscopy and opals

R.A. Ball & A.S. Malin

May 1974

56-57

Brazilian precious opal

P.A. Males

February 1975

 

 

152-154

Classification and nomenclature of precious opal

N.A. Clayton

155

Precious opal in Queensland

B.R. Senior

May 1975

171-173

Opal from Coolgardie, Western Australia

R.A. Ball

179-180

Notes on identification of Gilson synthetic opal

G.A. Tombs

181-189

Opal references & abstracts

R.A. Ball & N. Clayton

August 1975

208-209

Chinaman’s hats

K.A. Sheens

222-226

New synthetic gems set a problem

J.H. Oughton

November 1975

235-240

On the origin of volcanic opal from Houhlahan’s creek (near Teven)

I.A. Mumme,

L. Seibright & R. Ball

August 1976

327-328

Indonesian opal

B. O’Leary &

R.A. Ball

November 1976

359-363

Opal in Western Queensland

R.A. Ball & A. Daniels

February 1977

 

3-11

Black opal

B. O’Leary

November 1977

104-108

Natural or synthetic?

R.A. Ball

109-116

Synthetic opals

P.J. Darragh,

A.J. Gaskin &

 J.V. Sanders

February 1978

 

 

 

131-133

Identification of synthetic opal - A review

R.A. Ball

146-140

Slocum stone

P.J. Darragh &

J.V. Sanders

156-158

Imitation opal

R.A. Ball

November 1978

 

259-260

Recognition of synthetic opal

N.P. Jamieson

February 1979

 

297-299

Porous Gilson synthetic black opal

A.D.C. Robertson

307-310

Opal references & abstracts – Part 2

R.A. Ball & N. Clayton

May 1979

334-336

Opal references & abstracts – Part 2

R.A. Ball & N. Clayton

August 1979

 

359-361

Treated Brazilian opal

G. Brown & J. Snow

362

Opals from the air

From UNIKEN

363-366

Opal references & abstracts – Part 2

R.A. Ball & N. Clayton

November 1979

 

383-385

Suggestions for nomenclature of opals

J.D. Altmann

386

Synthetic opal for natural opal

R.A. Ball

May 1980

18

The opal: Gem of mystery

Anon

August 1981

161-165

Jelly opal from White Cliffs

J.V. Sanders

February 1982

213-218

New synthetic opal made of plastics

N. Horiuchi

August 1982

305-310

Common opal and potch opal

R.A. Ball

November 1982

 

324-235

Honey opal

R.A. Ball

345

More synthetic opal

G.A. Tombs &

W.J. Joris

February 1983

12-16

Precious opal from new Zealand

R.a. Ball

August 1983

 

71-74

Certification of opal

G. Sherman

75-78

A proposal for classification of opals

J.V. Sanders

November 1983

129

Crystal opal (Letter to the Editor)

J.V. Sanders

May 1984

200

Crystal opal (Letter to the Editor)

J.S. Taylor

215

Opal pineapple (Mineralien Magazin)

S.M. review

February 1985

 

310-314

Black opal: A brief review

R.A. Ball

317

Opal pineapple (Letter to the Editor)

R.O. Chalmers

November 1985

435-445

Role of water in cracking of opal

G. Pearson

May 1986

45-51

Opals from Mexico

E. Gubelin

August 1986

129

The Australian opal fields

E. Sherman

November 1986

 

 

143-150

Opal pineapples from White Cliffs

G. Pearson

152

Boulder opal triplet imitating natural solid boulder opal

R. Brightman &

D. Sandeman

February 1987

175-77

More on crystal opal

B. O’Leary

May 1987

213-215

A system for evaluation of opal

S. Haugen

222

On the structure of sedimentary opal

Editor

August 1987

 

251

Australian triplet opals (Letter to the Editor)

L, Cram &

J.V. Sanders

252

Crystal opal and catamites (Letter to the Editor)

F.H. Thrupp

257-258

Pronounced flow structure in opal

J. Koivula

267

Japanese synthetic jelly opal

G. Brown & J. Snow

November 1987

 

 

287

Unusual opal triplet

G. Brown & J. Snow

296-300

LWUV fluorescence of gemstones; A photographic review

J. Snow & G. Brown

February 1988

323-327

Precious opal and the weathered profile at Coober Pedy

R.S. Robertson &

D.C. Scott

November 1988

464

Impregnated opal

G. Brown & J. Snow

February 1989

24-26

Black-dyed synthetic opal

G. Brown &

P. Callaway

May 1989

48-51

Siliciophite: Australian cat’s-eye opal

G. Brown

65

Unusual opals

G. Brown, J. Snow & H. Bracewell

August 1989

93-98

A gemmological study of ‘Opalite’ and ‘Opal Essence’

J. Koivula & R. Kammerling

101-103

Yundamindera fire opal

G. Brown &

H. Bracewell

November 1989

148-152

An investigation of three imitation opalised shells

J. Koivula &

R Kammerling

276-277

Imitation opalised shells (Letter to the Editor)

M. Benjamin

August 1990

285

Scenic Peruvian opal

G. Brown et al.

November 1990

 

332-333

Imitation opalised shells (A reply)

J. Koivula &

R. Kammerling

February 1991

 

 

 

 

352-355

Examination of a plastic coated ‘sugar treated’ opal

R. Kammerling &

J. Koivula

384, 382

Significant Australian opals

Anon

May 1991

 

420-421

Carved opal doublet

G. Brown, S, Kelly & H. Bracewell

422

Black pained opal

G. Brown, S, Kelly & H. Bracewell

November 1991

498-501

Plastic imitation opals purchased in Thailand

R. Kammerling,

J. Koivula & E. Fritsch

February 1992

 

 

7-12

The Mintabie opal field.

I.J. Townsend

18

Cause of colour in opal (Letter to the Editor)

G. Brown

19-21

Novel assembled opals from Mexico

R. Kammerling &

J. Koivula

May 1992

40-41

Robotic opal cutting

A. Cody & G. Brown

February 1993

 

 

145-148

An historical note on the colour phenomenon in precious opal.

D. Hoover

162-163

A composite imitation of crystal opal

R. Kammerling &

J. Koivula

May 1993

195-196

Leopardwood mosaic opal

M. Sawicki &

G. Brown

August 1993

223-224

Eric saved

Editor

November 1993

 

252-256

Some far northern opal diggings in South Australia

G. Brown, J. Townsend & K. Endor

August 1994

359-361

A brief report on Indonesian opal

C. Lambert &

G. Brown

November 1994

374-376

Opal – Australia’s National Gemstone

A. Bartram

2nd Quarter 1995

64, 61

Grawin Rainbow

B. Parker

Jubilee issue 1995

91-108

Gemstones of NSW

R. Coenraads

120-128

Gemstones of Queensland

A.F. Wilson

131-135

Gemstones of South Australia

I.J. Townsend

1st Quarter 1996

226-232

Dyed opalised sandstone and conglomerate: A new gem product from Andamooka

J. Keeling &

I.J. Townsend

3rd Quarter 1996

296-300

The true story of white Cliffs

G. Rowe

303-309

Ethiopia: A new source for precious opal

D. Hoover,

T. Yohannes &

D. Collins

4th Quarter 1997

486-496

A new era for opal nomenclature

A. Smallwood

2nd Quarter 1998

 

58-61

An occurrence of microcrystalline opal, Nipple mountain, Kelowna, British Columbia, Canada

R. Coenraads &

R. Pogson

3rd Quarter 1998

112-113

An ?Australian synthetic opal

G. Brown

1st Quarter 1999

198-201

New opal cutting factory at Khao Yai, Thailand

R. Coenraads &

P. Elmer

2nd Quarter 1999

 

 

223-224

French opal

G. Brown

230-231

White Cliffs: Australia’s first commercial opal field - A century of history

G. Rowe

4th Quarter 1999

347-348

Statement respecting the opal industry at White Cliffs

T.C. Wollaston

1st Quarter 2000

363-237

A preliminary investigation of precious opal by laser Raman spectroscopy

A. Smallwood

2nd Quarter 2000

416-430

Papers on opal previously published in The Australian Gemmologist

Editor

3rd Quarter 2000

458-465

Present Russian synthetic and enhanced gemstones

V. Balitsky

467-472

Diffraction colours of opal: First spectrophotometric data

M. Ostrooumov & H.A. Talay

4th Quarter 2000

534-539

Australia’s gemstone resources and their markets

G. Brown

1st Quarter, 2001

38-39

The geology of Australian opal deposits

J. Townsend

40

A new theory for the genesis of opal

J.H. Behr, K. Behr, J.J. Watkins

2nd Quarter 2002

207-210

The Springsure deposit of Precious opal.

Roy Beattie

2nd Quarter 2002

230-233

Mexican gem opals: Nano and microstructures, origin of colour, comparison with other common opals of gemmological significance

E. Fritsch , Ostrooumov, A, Barreau, D. Albertini, A.-M. Marie, B. Lasnier, J. Wery

242-243

Interesting American opals: Wood replacement

I.J. Koivula & M. Tannous

244-246

Louisiana opal

G. Brown

3rd Quarter 2002

270-177

Classification of natural opal; type 1

J. Schellnegger

278-282

Some aspects of precious opal synthesis

S.V. Filin, A.I. Puzynin, V.V. Samoilov

4th Quarter 2002

273-277

Update on Australia’s gemstone & pearl resources

G. Brown

287-194

Australian sedimentary opal: Why is Australia unique?

D. Horton

3rd Quarter 2003

437

Notes on identification of Gilson Synthetic opal – Reprinted V12(6)

G. A. Tombs

 

438-447

35 years on a new look at Synthetic opal

A. G. Smallwood

 

2nd Quarter 2004

50-58

The Origin of Precious opal – A New Model

Byron Deveson

1st Quarter 2005

221

Papers pf Gemmological Interest- Precious volcanic opal from the Raduznoe deposit Russia,.photo and authors only

IAGOD – Conference

V.B Tishkina ,

M.I Lapina

2nd Quarter 2005

254-259

Opals from Java

H. Sujatmiko, H.C Einfalt, U. Henn


2.  Other Opal References – By subject.
 
2.1 Evaluation
 
Schellnegger, J. (2002) Classification of natural opal type 1. Australian Gemmologist, 21, Number 7, 269-277.
 
Smallwood, AG (2003) Evaluation of carved Lightning Ridge Black Opal. The NCJV Valuer, 21, Number 2, 2-7.
 
Cody A. Australian Precious Opal, A Guide Book for Professionals, 1991, 17, 41.
 
Downing PB - Opal identification and Value, Majestic Press 1992.
 
Evans PR - Opal, The Professional Valuation and Classification Guide.
 
Cram Len – Various.
 
Aracic Stephen – Discover opals .
 
2.2 Synthetic opals
 
Smallwood, AG. (2003) 35 years on A New look at Synthetic Opal. Australian Gemmologist, 21, Number 11,
 
Schmetzer K, An Investigation of the Synthetic Products of Gilson Showing a Play of colours, Journal of Gemmology Vol:19, No1, January 1984, p27.
 
Gunawardene M, Mertens R. - Gilson Created Fire Opal Imitation with Play if Colours - Journal of Gemmology Vol:19, No1, January 1984, p43.
 
Darragh PJ, Perdrix, JL, Notes on Synthetic Precious Opal. Journal of Gemmology, Vol 14, p215.
 
Darragh PJ, Perdrix, JL, Synthetic Opals, Australian Gemmologist, Volume 13, No4.
 
 
2.3 Synthetic Imitation opals
 
Burch CR, A Re-examination of Slocum Stone - with particular emphasis on inclusions. - Journal of Gemmology Vol:19, No.7, July 1985, p586.
 
Scarratt K, Kammerling RC, Koivula JI, Opalite Triplets - new imitations of opal. Journal of Gemmology Vol 23, No.8, 1993.
 
Horiuchi N, New Synthetic Opal Made of Plastics, Australian Gemmologist, February 1982, p213.
 
Ball RA, Imitation Opal, Australian Gemmologist, February 1978, p156.
 
Campbell ICC, Klienstubber A, Thomas AE, Some Comparisons between natural, gilson, inamori and simulated opals. South African Gemmologist, February 1987, p3.
 
Darragh PJ, Sanders JV, Slocum Stone. Australian Gemmologist, Volume 13, No.5, February 1978, p146.
 
2.4 Natural Imitation Opal
 
Weldon R, Ammolite: The colourful fossil gem - Jewellers Circular Keystone, June 1992, p46.
 
Sweaney, JL, Fire Agates of Deer Creek, Gems and Gemology, Spring 1979, p130.
 
2.5 Treated opals
 
Mitchell K, Oiled opals, Journal of Gemmology Vol:18, No.4, 1982, p339.
 
Brown, G. Treated Andamooka Matrix Opal, Gems and Gemology. Vol 27 (2), p100.
 
Keeling, J.L. Townsend, I.J, Dyed Opalised sandstone and conglomerate, Australian Gemmologist, Volume 19,No.5, p226.
 
3 Scientific References
 
ALONSO, P.J., HALLIBURTON, L.E., KOHNKE, E.E. & BOSSOLI, R.B., 1983. X-ray induced luminescence in crystalline SiO2. Journal of Applied Physics 54/9, 5369-5375.
 
ARACIC, S., 1996. Discover opals before and beyond 2000, with surface indications. Digital Press Company, Brisbane. Australia (limited edition).
 
AUSTIN, G.T., (1991). Gemstone production in Arizona, Colorado, Idaho, Montana, North Carolina, Oregon, Maine, Utah, Nevada and Tennessee. Mineral Industry Surveys, Bureau of Mines, US Department of the Interior, 13.
 
Australian Government Gazette, 1993. No. S229.
 
 
BALL, R.A., 1983. The structure of opal and opal simulants. University of New South Wales, Msc Thesis, Sydney, NSW, 85pp. (unpublished).
 
BALL, R.A., 1986. The structure of some opals and opal simulants, Gemmological Association of Australia, Sydney, NSW, Research Diploma, 43pp. (unpublished).
 
BALL, S.H., 1950. A Roman Book on Precious Stones. Lorrin L. Morrison and the Gemmological Institute of America, Los Angeles.
 
BARNES, L.C., TOWNSEND, I.J., ROBERTSON, R.S. & SCOTT, D.C., 1992. Opal, South Australia’s Gemstone. South Australian Department of Mines and Energy Handbook Number 5. Revised edition 1992.
 
BARTOLI, F., BITTENCOURT, ROSA D., DIORISSE M., MEYER, R., PHILLIPPY, R. & SAMAMA, J., 1990. Role of aluminium in the structure of Brazilian opals. European Journal of Mineralogy 2, 611-619.
 
BAUER, H.L. & STAAZ, M.H., 1951. Virgin Valley opal district, Humbolt County, Nevada. USA Department of the Interior, Geological Survey Circular, No. 142.
 
BAUER, M., 1969. Precious Stones. Charles E Tuttle Company, Japan, 373-388.
 
BROOKS, J.H., 1967. A Prospectors Guide to Opal in the Yowah-Eromanga Area. Queensland Government Mining Journal 68/792, October 1967, 453-458.
 
CARR, S.G., OLLIVER, J.G., CONOR, C.H.H. & SCOTT, D.C., 1979. Andamooka Opal Fields: The geology of the precious stones field and the results of the subsidised mining program. Geological Survey of South Australia, Report of Investigations 51.
 
CHIANG, Y.M., BIRNIE, D.P. & KINGERY, W.D., 1997. Physical Ceramics, Principles for Ceramic Science and Engineering. John Wiley and Sons, Inc., New York.
 
COLE, S.H. & MONROE, E.A., 1967. Electron Microscope studies of the structure of opal. Journal of Applied Physics 38/4, 1872-1873.
 
CONNAH, T.H., 1967. A prospectors guide to opal in Western Queensland. Queensland Government Mining Journal 67/771, January 1967, 23-39.
 
CRAM, L., 1998. A journey with colour: a history of Queensland opal 1869-1979. Kingswood Press, Brisbane, Australia.
 
CSIRO Patent No. 418170, 1964. Opaline materials. Commonwealth of Australia, Patent Specification 50029/64.
 
DABDOUB, T., 1985. Opal report from Honduras: “the fire still burns”. Tropical Gem Explorations, Metaireie, Louisiana, USA.
 
DAKE, H.C., FLEENER, F.L. & WILSON, B.H., 1938. Quartz Family Minerals. McGraw Hill Book Company Inc, New York, Ch. 13, 239-254.
 
DARRAGH, P.J., GASKIN, A.J. & SANDERS, J.V., 1976. Opals. Scientific American 234/4, 84-95.
 
DARRAGH, P.J., GASKIN, A.J. & SANDERS, J.V., 1977. Synthetic opals. Australian Gemmologist 13/4, November 1977, 109-116.
 
DARRAGH, P.J., GASKIN, A.J., TERRELL, B.C. & SANDERS, J.V., 1966. Origin of precious opal. Nature 209, No. 5018, 13-16.
 
DOWNING, P.B., 1992. Opal Identification and Value. First Edition, Majestic Press, Tallahassee USA.
 
DUDA, R., 1996. Excursion Notes: Field Trip U3 East and Central Slovakia. International Mineralogical Association, Congress Notes 1996.
 
ECKERT, A.W., 1997. The World of Opals. John Wiley and Sons, Inc, New York.
 
EYLES, W.C., 1964. The Book of Opals. Charles E Tuttle Company, Japan.
 
FLÖRKE, O.W., GRAETSCH, H., MARTIN, B., ROLLER, K. & WIRTH, R., 1991. Nomenclature of micro- and non-crystalline silica minerals based on structure and microstructure. Neues Jahrbuch für Mineralogie, Abhandlungen, Stuttgart 163/1, 19-42.
 
FRITSCH, E. & ROSSMAN, G.R., 1988. An update on colour in gems. Part 3: Colours caused by band gap and physical phenomena. Gems and Gemology 24, 81-102.
 
FRONDEL, C., 1962. The System of Mineralogy. Seventh Edition, Volume III, Silica Minerals, John Wiley and Sons, Inc. New York, 287-306.
 
GASKIN, A.J., 1967. Opals. Australian Natural History 15/10, 319-323.
 
HAWTHORNE, F.C., 1988. Spectroscopic methods in mineralogy and geology. Reviews in Mineralogy 18, Mineralogical Society of America.
 
HEANEY, P.J., PREWITT, C.T. & GIBBS, G.V., 1994. Silica, physical behaviour, geochemistry, and materials applications. Reviews in Mineralogy 29, Mineralogical Society of America.
 
 
HEYLMAN, E.B., 1983. Opal localities in west central Mexico. Lapidary Journal 37/4, 598-602.
 
HOOVER, D.B., YOHANNES, T.Z. & COLLINS, D.S., 1996 Ethiopia: A new source for precious opal. Australian Gemmologist 19/7, 303-307.
 
ILER, R.K., 1979. The Chemistry of Silica, Solubility, polymerisation, Colloid and Surface Properties, and Biochemistry. John Wiley and Sons, Inc, New York.
 
JACKSON, C.F.V., 1902. The opal mining industry and the distribution of opal deposits in Queensland. Queensland Department of Mines Publication 291, 1958, (Reprinted from Publication 177).
 
JONES, J.B., BIDDLE, J. & SEGNIT, E.R., 1966. Opal genesis. Nature 210, No. 5043, 1353-1354.
 
JONES, J.B., SANDERS, J.V. & SEGNIT, E.R., 1964. Structure of opal. Nature 204, No. 4962, 990-991.
 
JONES, J.B. & SEGNIT, E.R., 1971. The nature of opal. 1. Nomenclature and constituent phases. Journal of the Geological Society of Australia 18/1, 57-68.
 
JONES, J.B. & SEGNIT, E.R., 1972. Genesis of cristobalite and tridymite at low temperatures. Journal of the Geological Society of Australia 18/4, 419-422.
 
KALOKERINOS, A., 1975. Australian Precious Opals. Thomas Nelson, Sydney, 1975.
 
KAMMERLING, R.C., KOIVULA, J.I., & FRITSCH, E., (eds). Gem News. Gems and Gemmology. 31/2, 137-138.
 
KROCH, N.J. & COOPER, W., 1983. Commentary, Queensland Opal. Queensland Department of Minerals and Energy, 15pp.
 
KUNZ, G.F., 1938. The Curious Lore of Precious Stones. Halcyon House, New York 7th Printing.
 
LAMBERT, C. & BROWN, G., 1994. A brief report on Indonesian opal. Australian Gemmologist 18/11, 359-361.
 
LANE, M.E. III, 1983. Microstructural ordering in synthetic opals: An X-ray diffraction and infrared and Raman spectral study. Wichita State University, Msc Thesis, Wichita, USA, 60pp. (unpublished).
 
LANGER, K. & FLÖRKE, O.W., 1974. Near infrared absorption spectra (4000-9000 cm-1) of opals and the role of water in these SiO2.nH2O minerals. Fortschrite der Mineralogie 52/1, 17-51.
 
LEECHMAN, F., 1961. The Opal Book. Ure Smith, Sydney.
 
MacNEVIN, A.A. & HOLMES, G.G., 1979. Notes on precious opal and its occurrence in New South Wales. Geological Survey of NSW, Report GS 1979/268.
 
MALLORY, L.D., 1969. Opal mining in western Mexico. Lapidary Journal 23/3, 420-428.
 
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