Desert Discovery Center, Barstow, CA---March 23, 2002
Submitted
by Al Wilkins, Secretary
Present: Mary
Aruta, Garth Bricker, Bob Housley, Bill & Pat Kent, Paul Malone, Walt
Margerum, Gene Reynolds, Bob Reynolds, Jennifer Rohl, Al Wilkins
Treasurer’s
Report: Bob Housley reported that
SCFM was solvent. He indicated that he
had submitted the necessary paperwork to apply for membership in CFMS, in order
to secure, among other things, insurance to protect the club and its officers
and agents while conducting club business.
Along with the application, Bob sent in $4.50 for each SCFM member as of
12/31/01. The application is to be
considered at the next CFMS Board meeting in April 2002. Bob H. added that lots of copies of
“Minerals of the Mojave” are still available.
Mary volunteered to try to sell them at the Desert Research Symposium on
April 20. Bob H. will attempt to drop
them off with Mary or Bob R. before that time.
“Minerals
of California” Photo Exhibit: Bob Reynolds, Mary Aruta and
Bob Hilburn, curator of the Desert Discovery Center (DDC) in Barstow, have
collaborated to mount 33 photos on poster board and then hang them on the west
wall of the DDC with Velcro fasteners.
Some of the photos were donated by Sugar White and by Anthony Kampf of
the L.A. County Museum. They cover 5
distinct themes---Mojave Sulfate Minerals (7); Wulfenite from the Blue Bell
Mine (6), Pseudomorphs (6); Hexagonal Crystals (7); and California Gemstones
(7). Another 18 photos featuring
“Minerals of Mexico” have been mounted on foam board and are on the table
displays at the DDC. We also have
another collection of “Minerals of Africa,” runners-up from the Werner Lieber
Photo Contest in Tucson, which have not yet been displayed. Bob R. indicated that the Maturango Museum
in Ridgecrest and the Shoshone Museum may be interested in similar photo
displays, and that perhaps several of the local desert museums could rotate
photo displays on various themes.
Jennifer is currently working on loading the photo images on the SCFM
website. Bob R. indicated that he would
like museum curators to request certain minerals themes before he compiles
photos to send them.
It was proposed that each of us
should bring our highest quality California thumbnails and small cabinet
specimens to an upcoming meeting to be arranged at JMCC, so that they can be
digitally photographed at that meeting and then returned home to their owners
the same day. Walt has a 2-megapixel
digital camera which he will set up and experiment with. He indicated a tif format would yield better
image quality than jpg and that the largest photo that could be produced from a
digital image in either case would likely be 8” x 10”, which all those present
seemed to think was acceptable. Gene
offered to bring in his double-tube fiber-optic light source for this purpose.
Next
SCFM meetings: The date and site of the
next SCFM meeting is still pending. Al
will call Garth next week to find out what he has heard from Cal Graeber
regarding his availability for a future meeting at the Fallbrook Museum. Bob R. will talk to Mary Burns at the JMCC
regarding the availability of that site as well. Gene reported that the JMCC classroom is now heated,
air-conditioned, and carpeted. Bob
R. recommended investigating the U.S. Borax Visitor Center or the 20 Mule Team
Museum in Boron as possible SCFM meeting sites for the future. Temecula also has potential. He also reported that the new convention
center at Ryan is eager to host the SCFM meeting in October, perhaps to focus
on borates. He advised up to think
about who we would like to hear speak, especially given the recent passing of
our friend Jim Minette; the name of Bill Smitheram, whose father had previously
worked at Ryan, was raised. Bob R.
indicated that he had not as yet broached the topic of a field trip in
conjunction with the Ryan meeting.
There is a need to update our collection of borate photos before the
Ryan meeting.
Upcoming
Events: SCMM meeting – June 15, 2002 @ JMCC
NCMA Micromount Conference June
22-23, 2002 @ Pollock Pines, CA
Web
site address: http://www.mineralsocal.org, then click
on Southern California Friends of Mineralogy in the upper right hand
corner. If you have new locality
information, please access that section of the site to complete a locality
form.
Secretary’s
Note: As the newly appointed
Secretary of SCFM, I would like to offer the alternative of e-mail transmission
of the SCFM meeting minutes/newsletter, for your convenience and to save the
group mailing costs. If interested,
please send your e-mail address to: alan.j.wilkins@kp.org. If I don’t hear from you, you will continue
to receive SCFM mailings at your snail mail address. I would also like to begin a new feature
spotlighting minerals with California type localities. This issue, I will feature benitoite, the
California state gemstone. I would also
like to encourage all SCFM members to relay any item(s) of general
interest to me for inclusion in future newsletters. In addition to my e-mail address above, I can be reached by FAX
at (949) 589-8608 or at: 23202 Via
Celeste, Coto de Caza, CA 92679-3919.
Current
SCFM Officers: President – Bob Reynolds; Vice-President
– Garth Bricker;
Treasurer – Bob
Housley; Secretary – Al Wilkins
SCFM Board: Bob Reynolds; Jack Nieburger; Dan McHugh; Kay
Robertson; Bob Varish
National FM Board of
Directors: Bob Reynolds; Jack Nieburger
SCFM
Mission Statement: Members of the Southern
California Chapter of the Friends of Mineralogy (SCFM) are collectors, museum
curators, amateur and professional mineralogists, and educators devoted to
propagating interest in mineralogy. For
all our diverse backgrounds, we are united in our desire to see minerals
appreciated and understood. Our goals
are to bring about a coalescence of professional and amateur mineralogists, to
offer the Chapter’s services and resources to Southern California natural
history museums, and with them to establish definitive, comprehensive
collections of California minerals.
SCFM is a non-profit organization that meets 6 times each year, at a
variety of mineralogically interesting institutions in Southern California, and
hosts an annual symposium on topics of interest to professional and amateur
mineralogists alike. Museum workshops
in March and October supplement general meetings. Annual membership dues of $10 include membership in the national
organization, Friends of Mineralogy.
SCFM is not responsible and cannot be held
responsible or liable for any person’s injuries, damages or loss of property at
or traveling to or from any general meetings, board meetings, workshops, field
trips, or any other SCFM event.
2002 SCFM Dues: If a red dot appears to the left of the address label on this newsletter, then your 2002 SCFM dues are outstanding. In that case, please send your check for $10 per member to SCFM Treasurer Bob Housley @ 255 S. Wilson Ave. #2, Pasadena, CA 91106.
BENITOITE - THE CALIFORNIA STATE GEMSTONE
by Al Wilkins
Classification:
Cyclosilicate.
Formula:
BaTiSi3O9.
Crystallography: Hexagonal
(P6c2).
Trigonal and hexagonal plates and platelets: {0001}, {0111), {1011},
{1010}, {1012}, {10.1.9.10}. Crystals
are triangular, flattened on the c axis,
and pyramidal or tabular.
Color:
Blue
(various shades), also colorless and white; rarely pink to purplish blue.
Luster:
Vitreous.
Streak:
White.
Hardness:
6-6.5.
Specific
gravity: 3.65-3.70.
Cleavage:
{1011},
imperfect.
Fracture:
Conchoidal
to uneven, brittle.
Toughness:
Fair;
brittle.
Refractive
indices: o = 1.756-1.759; e =
1.802-1.804. Uniaxial (+).
Pleochroism:
Strong: o
= colorless; e = blue.
Clarity:
Translucent
to transparent.
Birefringence:
0.043-0.047.
Dispersion:
0.046.
Fluorescence:
Intense bluish white under SW (254 nm).
Occ. dull red under LW (365 nm).
Cathodo-luminescense:
Intense blue.
Stability:
Sensitive
to rapid temperature changes and ultrasonic vibration.
Solubility:
Insoluble in hydrochloric
and sulfuric acids, but readily attacked by hydrofluoric acid.
Faceting
information: Critical
angle - 34.7o; Optimum crown angle - 38o; Optimum pavilion
angle - 41o.
Type
locality: Benitoite
Gem mine (previously the “Dallas Gem mine”), San Benito Co., CA.
In 1907, J.M. Couch of Coalinga, grubstaked by R.W. Dallas, was camping
in a wooded
glade in the Diablo Range above the
mercury-mining town of New Idria. Waiting
in his bedroll for the morning chill to subside, he was surprised to see the sun
reflected by “thousands of blue gems” on the slope above his camp.
Specimens were delivered to lapidary Harry U. Maxfield of Fresno, who
declared the stone spinel, finding it too soft to be sapphire.
He showed some of the stones to George Eacret of Shreve & Co., one of
the largest jewelry stores in San Francisco at the time, who believed they were
sapphires. Eacret used a
dichroscope to determine that the stone was doubly refractive and delivered a
sample to Professor George D. Louderback of the University of California
(Berkeley). Louderback analyzed the
material, made extensive crystal drawings, and paid close attention to the etch
figures on each of the faces. The p
and ii faces were found to be
symmetrically unrelated, proving the existence of a 6-fold
axis. He eventually
concluded that the material represented a new mineral, which he named benitoite
after the county of its discovery and the river which had its headwaters nearby.
The subsequent atomic arrangement of benitoite determined by Zachariasen
(1930) confirmed Louderback’s conclusions.
Louderback described the three major minerals of the Benitoite Gem Mine
area—benitoite, neptunite, and joaquinite---in his classic paper in 1909.
Benitoite became an immediate sensation after Louderback’s description
in 1909, partly because of its beauty and partly because it was the first
mineral in the previously theoretical crystal class 6m2 (P6c2)—the
ditrigonal-dipyramidal class of the hexagonal crystal system, predicted
mathematically by Hessel some 77 years prior to its discovery.
Unlike the common cyclosilicates beryl, cordierite, and tourmaline, whose
structures are based upon circular rings of six SiO4 tetrahedra,
benitoite is based upon three tetrahedra linked together to form a triangular
group. Two other equally rare
minerals have now been identified as sharing this structure with benitoite:
bazirite [BaZrSi3O9], found most prominently on
Rockall Island, Inverness-shire, Scotland; and pabstite [Ba(Sn,Ti)Si3O9],
found only in the Kalkar limestone quarry in Santa Cruz Co., CA, now the site of
a housing development.
After the discovery of benitoite, the Dallas Mining Company built cabins
and corrals nearby, and mining equipment was hauled in by horse and wagons over
tortuous roads from Coalinga. Active
mining began in July 1907. Dallas
patented two claims of 20 acres each and mined the veins for benitoite gem
material between 1907 and 1912, when it ceased to be economical. The mine was not issued patent papers until 1917.
Dallas initially liberated benitoite from the natrolite veins with
chisels and a punch press; many crystals were broken this way.
HCl dissolution of natrolite was later showed to be effective, but was
judged to be too time-intensive, and the earlier, more primitive extraction
methods were again resorted to. After
1912, little further mining was done until the mine was leased by Miller
Hotchkiss of Firebaugh, CA in the 1940s, and a bulldozer was utilized for the
first time to work the mine tailings. From
1952 to 1967, Clarence Cole, a mineral dealer from Oakland, held the lease and
used a bulldozer and dynamite to enlarge the pit.
In 1966, Cole granted a sublease to Gerold Bosley of San Diego, backed by
the noted mineral dealer Josephine Scripps.
Cole died in 1967, and the lease was subsequently transferred to William
C. “Bill” Forrest of Fresno, CA and Elvis
L. “Buzz” Gray, currently of Missoula, MT.
Forrest and Gray purchased the mine from the Dallas family in 1987 and
remain the sole owners today. Most
of the best specimens of neptunite, benitoite, and jonesite have been produced
by Forrest and Gray, who initially hand-picked mineralized blueschist and loose
pieces of benitoite from the dump, then took great care in removing the
natrolite from the crystals they found. Since
1982, the owners have used a more mechanized recovery process utilizing a
front-loader feeding dirt and rock through a grizzly into a hopper, where
material is successively washed and screened, with visual inspection and
hand-picking of rough gem benitoite at the end of each work day.
By the end of 1996, the colluvium and eluvium at
the Benitoite Gem mine area had been nearly completely worked out, but a
new productive area to the west, downslope from the historic pit, was identified
in the spring of 1997. Still, only
limited production of benitoite gemstones is anticipated in the future.
It is estimated that a total of 2,500 carats of faceted benitoite was
produced from 1907 until 1967, when Forrest and Gray began working the mine; of
that, 1,000 carats were produced in the first four years of the mine’s
existence. Since 1967, Forrest and
Gray have produced about 2,000 carats of faceted benitoite.
An estimated 500 carats of faceted benitoite have entered the market from
other sources, such as the cutting of old rough and the faceting of mineral
specimens. Thus, a total of 5,000
carats of faceted benitoite was produced by the Benitoite Gem Mine as of 1997.
Good quality gems cut from benitoite are seldom larger than one carat,
since crystals are typically badly flawed and since the best color (along the e
axis) is seen in the disadvantageous direction in terms of flattening the
crystals. Of the faceted stones
produced by Forrest and Gray, 89% of them have been under 1 carat; 9% ranged
from 1 to 2 carats; and 2% have been over 2 carats; benitoite gemstones over 3
carats are exceedingly rare.
The benitoite mine, popularly called the “Dallas mine” until the
mid-1960s and subsequently as the “Dallas Gem mine,” has been designated as
the “Benitoite Gem mine” by its current owners, after the notation on U.S.
Geological Survey topographic maps of the site as the “Gem mine.” The mine is located on the southern end of the Diablo Range,
in the western San Joaquin Valley of California, 20 miles northwest of the town
of Coalinga, in the New Idria district. The
New Idria district was established in 1853 with the discovery of a rich mercury
deposit, but it is also known for its chromium, asbestos (short-fiber
chrysotile), gold, and gemstone resources.
The Benitoite Gem mine’s elevation is approximately 4,520 feet.
It is located on 40 acres of private, patented mining property, secured
by a locked gate, and patrolled regularly by law enforcement officers. Access from either the southwest or the northeast requires
about 20 miles of driving over a network of rough 4-wheel-drive trails
maintained infrequently by the U.S. Bureau of Land Management. Geologic maps of the mine were first prepared by Coleman
(1957), and later by Rohtert (1994) and Laurs (1995).
Laurs, Rohtert and Gray (1997) did extensive geologic mapping and
collected chemical data on blueschist minerals and whole-rock samples at all
known benitoite occurrences in the New Idria district.
Based on those studies, they have hypothesized that benitoite formed at
the Bentoite Gem mine when Ba and Ti were released by the alteration of
blueschist, and possibly greenstone, in the presence of magnesium- and
calcium-rich fluids generated during the regional metamorphism of serpentinite.
The Diablo Range is composed of rocks of the Jurassic Franciscan
formation (graywacke, shale, chert, and basalt), intimately associated with
serpentinite in the New Idria area. In
the Franciscan block containing the Benitoite Gem mine, graywacke has been
metamorphosed to greenstone and basalt to blueschist, subsequently altered to
felted masses of actinolite or crossite fibers. Solutions periodically percolating through fracture systems
there have formed veins consisting primarily of albite, crossite, and epidote.
The mineralized zone is at least 60 meters long, strikes N60oW,
dips moderately northeast, and is about 3 meters thick.
Benitoite crystals attached to the walls of cross-cutting veins are
generally well formed and of an exceptional blue color, while those filling pore
spaces in altered blueschist typically have a dull, frosted, porous appearance,
deriving from abundant inclusions. Common
benitoite inclusions are the amphiboles actinolite-tremolite and crossite; the
pyroxenes aegirine-augite and diopside; silica pseudomorphs after serandite;
reddish-brown neptunite; and honey-colored joaquinite-group minerals.
Other reported inclusions include albite, apatite, and greenish-gray
djurleite. Rarely, non-gem
benitoite crystals form star-shaped penetration twins via a Dauphine-type 180o
rotation about the c axis; only
nine twinned crystals have been recovered thus far by the current mine owners.
Tentative age data suggests that the benitoite crystallized about 12
million years ago, making it much younger than the enclosing blueschist, which
formed between 100 to 160 million years ago.
Minerals formed at about the same time as benitoite include albite,
apatite, jonesite, and the copper sulfides djurleite, digenite, and covellite. Later, natrolite coated the earlier-formed minerals and
filled most of the remaining pore spaces. Other
associated minerals include: neptunite, joaquinite, fresnoite, banalsite, silica
pseudomorphs after serandite, calcite, and aragonite.
Four other benitoite prospects in the New Idria district include: (1) the
Junnila claim, first worked in 1982, producing translucent, tabular crystals in
blue, colorless, or color-zoned varieties, averaging 1 cm in their maximum
dimension, though a few crystals of up to 2.6 cm have been suitable for
faceting; (2) the Numero Uno claim, producing pale blue, platy, euhedral
crystals up to 5 mm in diameter; pale blue to colorless tabular,
pseudo-hexagonal plates and rosettes up to 10 mm in diameter; and, less
commonly, tan grains, described as “pink” by Chromy (1969); (3) the Victor
claim, first staked in 1974, producing colorless benitoite platelets and
rosettes up to 5 mm in diameter; and (4) the Santa Rita Peak property,
controlled by the Kennecott Exploration Company, on which electron microprobe
analysis has revealed microscopic crystals of benitoite in altered blueschist.
All of the aforementioned localities are closed to public collecting.
Of these, only the Benitoite Gem mine and the Junnila mine have produced
gem-quality benitoite material, and only the former has yielded commercial gem
production.
Outside the New Idria district, benitoite has been found in situ at only four other areas. At the Big Creek-Rush Creek confluence, in eastern Fresno
County, small grains of stannian benitoite, containing up to 4.1 wt. % SnO2,
are found in gneissic metamorphic rocks near granodiorite, first reported in
1965. In Japan, benitoite was
reported in 1973 from albite-amphibole rock in a serpentine body along the
Kinzan-dani River, at Ohmi in the Niigata Prefecture, containing 1.77 wt. % ZrO2.
At Broken Hill, New South Wales, Australia, benitoite was reported in
high-grade granite gneiss in 1982. More
recently, 1-2 mm crystals of colorless, blue, and pink benitoite were detected
in gas cavities in syenite at the Diamond Jo quarry in Hot Springs Co.,
Arkansas. Two previously reported benitoite locations, Esneux and
Streupas in the Owithe Valley, Belgium (1928) and sands of the Eocene Cook
Mountain formation of southwest Texas (1931), have subsequently been
discredited.
The measured amounts of Ba, Ti, and Si in benitoite are remarkably
constant (BaO 37.09%, SiO2 43.59%, TiO2 19.32%),
regardless of color or locality, and fall near the ideal values that are
calculated from the chemical formula. The
appearance of benitoite crystals is quite variable, however.
A few are gemmy and deep to pale blue.
The vast majority, however, are translucent with whitish centers and blue
outer rims. Detailed electron probe
analysis by Laird and Albee (1972) indicated that the composition of the white
and blue parts of the crystal were identical. Those crystal faces having a stoney appearance are pale
blue-gray because of abundant crossite inclusions, and most of them contain
prominent etch pits. Average
benitoite crystal sizes are 1 to 1.5 cm, and crystals greater than 2.5 cm in
diameter are considered large. Wise
& Gill (1977) describe a well-formed crystal measuring 5.6 cm in the
collection of the Geology Department of Pomona College in California.
A fine matrix specimen obtained by Josephine Scripps in 1956, measures
21.6 x 12.7 cm (8.5" x 5") and is pictured in The
World’s Finest Minerals and Crystals by Dr. Peter Bancroft.
Benitoite is considered one of the most beautiful of all the rare gems
and, lacking cleavage, is one of the easiest to facet.
Its color varies from a very pale blue to a deep purplish blue; the color
of the finest benitoite (often referred to as “cornflower blue”) rivals that
of fine sapphire. Its dispersion
approaches that of diamond and is best shown when faceted as a round brilliant
or as a trilliant. Color zoning is
occasionally seen, especially in emerald-cut stones, which can display a
characteristic blue-to-colorless pleochroism when viewed face-up with the
unaided eye. The violaceous tints
are attributable to its strong dispersion (similar to that of diamond), often
apparent as the stone is turned. Colorless
gems are uncommon. Rare specimens
have a strong reddish component and exhibit pink-to-blue dichroism.
Heat treatment of lighter-colored material may result in an orange hue
similar to that associated with Imperial topaz; the orange color has not been
observed in untreated benitoite. Spectrophotometry
of blue benitoite reveals a broad peak at about 700 nm, most of which appears in
the near-infrared region. In spite
of much study of spectral data and the chemical composition of benitoite
specimens, a chromophore has not been identified; attributions of its blue color
to reduced Ti; trace impurities of V, Nb and Cu; crystal defects due to oxygen
deficiency; metal-metal charge transfer; traces of Zr at the Ti site; and traces
of Fe3+ have not been substantiated in the laboratory.
Distinguishing benitoite from other blue gemstones is generally not
difficult for a gemologist. Its
high birefringence, strong dispersion, and its blue-to-colorless pleochroism
distinguishes it from sapphire. Natural
and irradiated blue diamonds can have the appearance of lighter shades of
benitoite, but can be easily distinguished from benitoite by being singly
refractive and possessing a much higher refractive index.
Benitoite may be distinguished from tanzanite by its lack of the purple
trichroic component almost always present at some angle in tanzanite.
Sapphirine is generally too dark to be confused with benitoite, and
zircon does not possess the same hue. Cordierite
(iolite) and blue tourmaline (indicolite) show much lower dispersion, refractive
indices, and birefringence than benitoite.
In addition, benitoite commonly has distinctive growth-zoning and the
lint-like mineral inclusions described above.
The largest known faceted benitoite gemstone weighs 15.42 carats and was
cut from rough recovered in the early 1990s; another exceptional gem weighs
10.47 carats and was cut in the late 1980s.
A third benitoite gemstone worthy of mention weighs 7.53 carats (after
being re-cut) and is part of the National Gem Collection housed at the
Smithsonian Institution in Washington, D.C.
Gray and Forrest made a set of benitoite jewelry, consisting of a ring,
earrings, and a diamond necklace with a pendant centered with a flawless 6.53
carat pear-shaped brilliant benitoite in 1974.
The set was shipped to Zurich, Switzerland, where it was stolen from the
airport. All but the pendant was
recovered within a year of the theft.
Synthetic benitoite has been successfully grown in the laboratory, but
only in minute, colorless crystals that are too small to facet. Natural benitoite has an important industrial application in
electron microprobes, being used to align and adjust the beam size.
Benitoite is also employed as an analytical standard for Ba and Ti,
because of the consistency of its chemical composition.
The ultraviolet response of benitoite is interesting. Under SW (254 nm), benitoite fluoresces an intense
blue-white, the paler-colored cores frequently more vividly than the edges.
Under LW (365 nm), the cores fluoresce a dull red, while the edges are
non-fluorescent. Both SW and LW
responses are more pronounced in colorless and lighter-colored benitoite
specimens.
California State Bill AB-2404, proposed by Lucy Killea of the 78th
District and Rusty Areias of the 25th District, officially designated
benitoite as the California State Gemstone in 1984, taking its place with native
gold, the California State Mineral (designated 1965), and serpentine, the
California State Rock (also designated 1965).
The emblem of the California Federation of Mineralogical Societies is a
triangular form surrounding the famous Golden Bear Nugget (pictured on the
Centennial Volume of Minerals of
California—Bulletin 189). The
points of the triangle are truncated to represent the crystal form of benitoite.
CHRONOLOGICAL
BIBLIOGRAPHY:
Hessel
J.F.C. (1830) Krystallometrie. Reprinted
as: Nr.
88. Ostwald’s Klassiker der
exakten
Wissenschaften (1897), Wilhelm Engelmann, Leipzig.
Louderback G.D. (1907) Benitoite, a new California gem mineral (with
chemical analysis by W.C. Blasdale). University
of California, Department of Geological Sciences Bulletin 5, pp.
149-153.
Arnold
R. (1908) Notes on the occurrence of the recently described gem benitoite.
Science 27, No. 686, pp.
312-314.
Rogers A. F. (1908) Notes on the crystal form
of benitoite. Science
28, p. 616.
Louderback
G.D. (1909) Benitoite, its paragenesis and mode of occurrence.
University of California, Department
of Geological Sciences Bulletin 5, pp. 331-380.
Palache
C. (1909) Note on the crystal form of benitoite. American Journal of
Science 27, p. 398.
Sterrett
D. B. (1911) Benitoite. U.S.
Bureau of Mines and Minerals 1909 Yearbook, Part. 2: Non-metals.
Washington, D.C., pp. 742-748.
Bradley
W.W., Huguenin E., Logan C.A., and Waring C.A. (1917) Mines
and Mineral Resources of the Counties of Monterey, San Benito, San Luis Obispo,
Santa Barbara, Ventura. California State Mining Bureau, San Francisco, pp.
42-43.
Anten
J. (1928) Sur la composition lithologiques des psammites du Condroz.
Societe Geologique de Belgique,
Annales 51, pp. B330-331.
Zachariasen
W. H. (1930) The crystal structure of benitoite, BaTiSi3O9.
Zeist. Kristallogr. 74, pp.
139-146.
Lonsdale
J.T., Metz M.S., and Halbouty M.T. (1931) The petrographic characters of some
Eocene sands from southwest Texas. Journal
of Sedimentary Petrology 1, pp. 73-81.
Payne C.J. (1939) Dispersions of some rarer gemstones.
Gemmologist 9, pp. 33-35.
Pabst
A. (1951) Minerals of the serpentine area in San Benito County, California.
Rocks and Minerals 26, pp. 478-485.
Rase
D.E., and Roy R. (1955) On the stability and hydrothermal synthesis of
benitoite. American Mineralogist 40, pp. 542-544.
Coleman
R.G. (1957) Mineralogy and petrology of the New Idria district, California.
Ph.D. dissertation, Stanford University, Stanford, CA.
(See Dissertation Abstracts 17,
No. 17, p. 1533).
Couch O. (1961) The Benitoite Story. Independently
published, 10 pp.
Lee
D.E., Thomas H.H., Marvin R.F., and Coleman R.G. (1964) Isotopic ages of
glaucophane schists from the area of Cazadero, California.
U.S. Geological Survey Professional
Paper 475, pp. D105-D107.
Alfors
J.T., Stinson M.C., Mathews R.A., and Pabst A. (1965) Seven new barium minerals
from eastern Fresno County, California. American
Mineralogist 50, pp. 314-340.
Gross E.B., Wainwright J.E.N., and Evans B.E.
(1965) Pabstite, the tin analogue of benitoite. American Mineralogist 50, pp. 1164-1169.
Moller
W.P. (1965) Minerals of southern San Benito County, California.
Gems and Minerals 331, pp.
28-32.
Chromy B. (1969) Pink benitoite.
Gems and Minerals, No. 279,
p. 32.
Laird
J. and Albee, A.L. (1972) Chemical composition and physical, optical, and
structural properties of benitoite, neptunite, and joaquinite.
American Mineralogist 57,
pp. 85-102.
Chihara K., Komatsu M., Mizota T. (1973) A new strontium-titanium hydrous
silicate mineral from Ohmi, Niigata Prefecture, central Japan. Mineralogical Record 7,
No. 3, pp. 198-301.
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