IDOCRASE (Vesuvianite)
Relatively abundant in crystals but seldom providing clear areas for faceted gems of over 2 ct.; good cabochon material more common, jade-like material from California being called californite or, sometimes, “California jade.” Fairly hard but mainly cut for collectors.
INDICOLITE, see TOURMALINE Continue Reading »

HAMBERGITE
Very rare colorless gemstone; fairly hard but cut only for collectors; facet-grade crystals only from Madagascar but this deposit exhausted, and material now comes only from old collections;  clean gems  to 5 ct. considered large.

FIBROLITE (Sillimanite)
Very rare; hard, but very easily cleaved and few attempts to cut succeed; as waterworn transparent pebbles in gem gravels of Burma; collectors’ stone only.
Burma, facet-grade pebbles, 2-10 ct.    ct.    1.00-2.50
FLINT,   See   QUARTZ FLUORITE
Soft, cleavable, low refractive index, but occurs in many attractive hues and is commonly faceted for collectors; massive purple and white banded variety from England, known as “blue John,” has been extensively employed for or¬namental objects of considerable size, but the source of material appears de¬pleted and the industry dormant. Facet grade available in colorless, pale blue green, purple, yellow, and, rarely, in pink or red; cut gems to several hundred ct.
England, green, purple, fine, 10-100 ct.    gm.    .20-.30
Illinois, purple, yellow, fine, 100 ct.+    gm.    .05
Mexico, pale green, to 50 ct.    gm.    .20-.30
New Hampshire, fine green, to 200 ct.    gm.    .05-.35
Ontario, pale green, to 50 ct.    gm.    .25-.65
S. W. Africa, pale green, to 100 ct.    gm.    .05-.10
FRIEDELITE
Extremely fine-grained massive material from zinc mines of New Jersey; translucent; some resembles brownish carnelian in color; for cabochons and translucent faceted gems;  rare except at localities named;  a collectors’  gem.

GADOHNITE
A heavy black rare-earth mineral sometimes cut as a curiosity.
GARNET
The species and varieties of this group furnish many fine gems in a wide variety of hues; deposits widespread and some gem-quality garnets continually supplied to the market at relatively low cost; demantoids and spessartines in short supply; recently very fine rhodolite has appeared on the market from Tanzania and commands a high price in view of its beauty and the rarity of this variety in large sizes.
ALMANDITE
Many sources of facet-grade rough;  star rough    from Idaho in large  sizes;
colors from brownish-red and very dark to bright red to purplish-red of medium
intensity.
ANDRADITE
The classic variety of andradite is demantoid, noted for its beautiful intense yellow-green to emerald-green hues; rough formerly from Russia and now un¬obtainable; some roue;h from Italian alpine sources; rare.
GROSSULAR
Also known as hessonite or essonite; facet-grade material resembles the orange-red to orange hues characteristic of spessartine, for which species grossular has been confused; additionally, in colorless to very pale orange facet-grade material, and massive, resembling jade or idocrase; largest hessonites supplied by gem gravels of Ceylon, yielding cut gems to 15 ct. Softer than other garnets.
PYROPE

Invariably as small smooth-surfaced grains in eruptive rocks or surface gravels; seldom over 1-2 gm.; best color dark uniform red; to be colorful, most faceted gems should not be over 1-2 ct.
RHODOLITE
Formerly quite rare but recently available in large fine rough from Tanzania; color range medium to pale purplish-red to pale reddish-purple, almost resem¬bling some amethyst; produces fine brilliant gems.
GOETHITE
Massive, fibrous material sometimes cut into ornaments or cabochons dis¬playing bandings and weak chatoyancy; black with dark brown to yellow bandings.
Michigan    lb.    2.50
GOSHENITE,   See   BERYL GRANITE
Various types of granite and granite-like rocks have been used for ornamental objects of large size and sometimes for cabochons and tumbled gems (see UNAKITE); graphic granite displays interesting patterns of grayish quartz upon white  to  pale  tan  feldspar and has been made  into  spheres,  bookends,  etc.
Granites, various localities    lb.    .25-.75
GROSSULAR,   See   GARNET
GYPSUM
Ornamental objects made from compact varieties alabaster and satin spar, the latter chatoyant; white, pink, pale orange, pale brown, etc.; very soft but accepts a good polish; much worked in Italy into boxes, statuary, imitation fruits, etc.; accepts dye.

EMERALD, see BERYL
ENSTATITE
Available from India as corroded facet-grade crystals of dark greenish-brown to brown color; also showing 4-rayed star on nearly black background; faceted gems cut to 4-8 ct., but larger gems appear too dark; hard, tough, but cut only for collectors.
EPIDOTE
Abundant rock-forming mineral, sometimes cut in massive form for cabochons or for large ornamental items; facet-grade crystals cut for collectors, but while hard, are too dark to be attractive. Piedmontite is a massive variety sometimes cut in cabochons of an attractive deep rose color.
Baja California, Mexico, crystals, small clear    gm.    .15-.25
California, Kern Co., crystals with clear areas    gm.    .15—.25
Austria, Salzburg, fine clear crystals    gm.    .50-1.50
ESSONITE,   see   GARNET EUCLASE
One of the classic rarities; occurs in Brazil and Siberia in clear crystals ranging from colorless to pale straw-yellow, yellow, pale green, and blue; cleavable; cut only for collectors; cut gems over 5 ct. very rare.
Brazil, crystal sections, according to clarity and
color; blue costliest        ct.    1.50-20.00

DANBURITE
Hard gemstone suitable for transparent faceted gems but cut only for collectors; colorless crystals abundant from Mexico; rarely, pale yellow waterworn pebbles from gem gravels of Burma.
DATOLITE
Attractive faceted gems cut from very pale yellowish-green crystals; the finest are from Westfield, Massachusetts, and afford flawless gems to 5-6 ct. Unusual massive datolite, colored by copper and other minerals, occurs as warty nodules to 10″ diameter in copper deposits of Michigan; these are prized according to size and color, the least valuable being white, increasing in value toward red, reddish-brown, orange, etc., and sometimes cut for cabochons but mostly sliced and polished as cabinet specimens.
DEMANTOID,   See   GARNET DIAMOND
It is virtually impossible for anyone outside the established diamond cutting, selling, or trading organizations to obtain supplies of gem-quality diamonds except from Brazil, where a substantial quantity of diamonds is produced each year from river gravels by independent miners; the usual sources in Africa are closely controlled by the De Beers Syndicate, which grades the stones and places them on sale in London as lots, each lot containing various sizes and grades according to the established consumption records of the buyers who have traded with the syndicate in the past. Supplies are not abundant and few buyers of lots are willing to part with good stones if they can cut them themselves and realize a greater ultimate profit thereby. This situation, and the necessity for special lapidary equipment in order to cut diamonds, has resulted in few non-professional cutters attempting to cut this gemstone. Prices for rough rise very steeply with
quality and size and the figures given below are only an approximate guide. A full discussion of qualities appears in the next chapter.
DINOSAUR   BONE,   see   QUARTZ DIOPSIDE

Hard, durable, but seldom attractive colors; fairly steady supply of facetable dark green crystals from Madagascar; occasionally in pale green from Alpine localities and New York; also in attractive pale green waterworn crystals from gem gravels of Burma. The Madagascar material is so dark that gems over 5 ct. tend to be unattractive. Star diopside, but very dark, occurs in India.

VIOLANE
Massive, purple variety of diopside, sometimes used in collectors’ cabochons; rare; found in small patches in ore at Franklin, New Jersey, and at St. Marcel, Piemonte, Italy.
Massive, often admixed with other minerals    oz.    .50-.75
DIOPTASE
Vivid emerald-green crystals sometimes faceted into very small gems for col¬lectors; soft, brittle; rarely clean. Largest clear gems about l/£ ct.
Africa, crystal tips to 14″    ct.    .75-1.00
DOLOMITE
An abundant rock-forming mineral, some types of which are used for large objects; rare in clear crystals suitable for faceting; soft, cleavable, a collectors’ gem only.
New Mexico, colorless facet crystals to 15 ct.    ct.    .15-.60
New Hampshire, massive, tan, red & brown    lb.    .75
Michigan, “Kona” dolomite, mottled & colored,
DRAVITE, See TOURMALINE DUMORTIERITE,   See   QUARTZ

CALIFORNITE, See IDOCRASE CANCRINITE
Bright yellow to orange-yellow massive,    usually with  blue  sodalite;   seldom -
occurs large enough to provide pure-color    cabochons over i/2″ diameter;  soft,
brittle; collectors’ item only.
Ontario or Maine, massive    oz.    1.00
CARBORUNDUM, see SILICON CARBIDE CARNELIAN, See QUARTZ CASSITERITE
Bolivia, facet grade, according to size & color
Mexico, wood tin, brownish nodules
CATL1NITE
Soft,  easily  carved  stone  containing  pyrophyllite
reddish in hue; Indian “pipestone.”
South Dakota
CATSEYE SHELL, See SHELL
CELESTITE
A highly prized collectors’ item when faceted from colorless, flawless material; hard and tough but too rare to be used commercially; clear material only from outer zones of the dark brown crystals from Bolivian tin deposits. Massive fibrous variety known as wood tin sometimes cut cabochon. Faceted gems over 1-2 ct. rare; largest clean gems not
CERUSSITE
An extremely soft lead mineral, but capable of being cut into attractive faceted gems of considerable brilliance and dispersion; the best material is colorless; collectors’ item only. Also in excellent catseye material, but very rare.
CHALCEDONY, See QUARTZ CHERT, See QUARTZ CHIASTOLITE, See ANDALUSITE CHLORASTROLITE, See PUMPELLYITE CHLOROMELANITE, see JADEITE
CHONDRODITE
Excessively rare one-locality mineral from Tilly Foster iron mine, New York, as small transparent brownish-red crystals not over i/8″ thick; occasionally avail able from old collections; collectors’ gem only.
Facet grade, to 4 ct.    ct.    2.00-12.00
CHROMITE
Black, massive chrome ore, sometimes cut as a curiosity.
Maryland, California, or Oregon    lb.    2.50
CHRYSOBERYL
Very hard and durable; provides excellent gems for jewelry such as catseyes, chartreuse to yellow faceted gems, and alexandrites, the last noted for their color change from green in daylight to bright red under artificial tungsten light, the value depending on how distinct the change is, how vivid the colors, and, of course, size, freedom from flaws, etc. The finest alexandrites came from the Urals and rough is no longer obtainable; those from Ceylon tend to be brownish and display considerably less attractive colors; recently in fair to good small crystals from Brazil and as small crystals with good color change from Rhodesia. The best catseyes display a remarkably sharp silky white eye upon a highly translucent green to yellow background, the greenish hues being more desirable; also in alexandrite type but seldom showing good color change. Brownish to yellowish facet grade chrysoberyls are not highly prized commer¬cially because they resemble the cheaper gemstones, citrine and golden beryl; chartreuse-green faceted gems are much more esteemed and command good prices.
Brazil, greenish body color, add 15%-20% to above prices Brazil, alexandrite-type, weak color change, 3-4 ct.     ct.
End of Chrysoberyl Section
CIIRYSOCOLLA, See QUARTZ CI1RYSOPRASE, See QUARTZ
CITRINE, see QUARTZ CLEIOPHANE, see SPHALERITE
(XINOZOISITE
Sometimes available from Baja California as facet-grade crystals of brownish color; a collectors’ gem.
Brown to yellowish-brown, to 10 ct.    ct.    .25
COAL, see ANTHRACITE
COBALTITE
Produces interesting metallic luster cabochons of pink-silver color.
Ontario, massive pieces to i/2 lb.    lb.    2.50-4.50
COLEMANITE
Soft, fragile, and slowly perishable facet-grade crystals obtained from the bo¬rate deposits of California; collectors’ gem only.
Colorless to faint yellow, to 8 ct.       ,    ct.    .20-.75
CONCH, see SHELL
CORAL
Occurs in all shades from pale to dark pink or orange-pink, to various shades of red, to dark red (”ox-blood”); also brownish-red, and mottlings of several hues or with white; pure white is also commonly available. Mottled pieces are considered much less desirable. Flaws include worm borings and soft places, or discolorations due to decomposition in the case of coral fished up dead. Soft but fairly tough and capable of receiving fine detail in carvings and an excellent polish. Used in carvings, cabochons, beads, and as polished stem and twig sec¬tions set “as is” in jewelry or strung in necklaces in the case of slender twigs of about 1/16″ thickness. Some large branches are sold for table ornaments; especially prized and very rare are sea-floor stones upon which a handsome growth of coral is attached; however, fakes are common, consisting usually of sections of branches, sometimes polished, set into soft rock which lacks the white calcareous deposits typical of true sea-floor pebbles. Values vary widely accord¬ing to tastes developed in individual countries; pelle d’angelo, or “angel’s skin,” is highly prized in Europe and in the Orient, its color being a pure rose; also valued in the Orient is pure white, but yellowish-tinged varieties are unaccept¬able; intense pink appears to be valued by everyone, but darker hues to deep red (”ox-blood”) are more esteemed in the United States. Large masses increase sharply in value because of the considerable rarity of old but perfect coral branches. Trade  terms used  for various grades of coral  are:   Sardinian, hard material of excellent quality; Italian, good quality in all shades from white to red; Moro, a fine-quality deep red Japanese type; tosa, average Japanese coral; Sicilian and Algerian, lesser qualities of Mediterranean coral; and Japanese coral, used to designate pieces that are mottled white and red.
Black coral is a different marine organism, lacking the calcareous skeleton of the true coral; its stems and branches consist of intensely black organic matter of great toughness; supplied from Pacific waters mainly; in vogue foi black, light-weight jewelry, accepts a fine polish; thick stem sections of aboui 1″ are liable to split along annular growth rings.

CORDIERITE, See IOLITE
CORUNDUM
Includes ruby, sapphire, and star stones; red hues are called ruby but pinks and all other colors are called sapphire with the implication that the rough is suitable for gem purposes; otherwise it should be called by the species name. In recent years opaque to barely translucent red corundums have been sold as “ruby,” particularly from India; needless to say they command but a very small fraction of the price received for real ruby in equivalent sizes. Finest sapphires are intensely hued, blue being the favored color; also prized are amethystine hues, orange, and rich pink; yellows are not as desirable for jewelry purposes while most greens tend to be somewhat dingy in hue, although very fine Australian stones have been found. Best star stones show distinct six-ray stars upon a richly-colored background whether red as in ruby or blue as in sapphire; as background colors depart from these hues the values drop sharply; the most abundant and cheapest star sapphires are only faintly blue, purplish, or merely pale gray to nearly white. In terms of size, star stones reach as much as 40 cts. in ruby and several hundred cts. in sapphire; faceted rubies over sev¬eral cts. weight are rare but sapphires commonly occur in sizes of many carats. Hard, durable; a standard gemstone. Good rough always difficult to obtain be¬cause the best material in largest sizes is cut locally and only the leftovers are sold outside the country.
RUBY
The finest rubies occur in the gem gravels of Burma; good rubies also from
Thailand and pale rubies from Ceylon; very rarely, small rubies of good color
from gravel deposits  in United States and Australia.  Extremely  expensive  in
rich red color, costs increasing rapidly with size and freedom from flaws.
Burma, fine reds, if available, 1-4 ct.    ct.    10.00-100.00
“     “    “        5-6 ct.    ct.    15.00-300.00
“     “    “        7-10 ct.    ct.    20.00-600.00
“     “    “    over 10 ct.    ct.    30.00-1000.00+
STAR   RUBY
Burma, fine star, if available, 1-10 ct.    ct.    5.00-550.00+
SAPPHIRE
The best rich blue sapphires occur in the gem gravels of Burma, sometimes in sizes large enough to facet gems of several hundred carats weight; fine rich blues also occur in Thailand but are usually much smaller; fine pale blues characteristic of Ceylon gravels; very small but fine colors from Yogo Gulch, Montana; fair to good sapphires from Australia especially in yellows and greens.
SYNTHETIC   RUBY   AND   SAPPHIRE
Star boules are not commercially available, all being used to cut finished gems in behalf of designated marketing companies; facet-grade boules available in any color and in any quantity. Synthetic ruby crystals grown by Chatham are avail¬able under the name “cultured ruby”; they closely resemble natural ruby crystals in respect to properties and inclusions.
CROCOITE
Small, brilliant red-orange transparent crystals only from Tasmania; faceted gems cut from them are far too soft to be used for any purpose except as col¬lectors’ items.
Prismatic crystal sections, i/g”-1^” long    ea.    .35-.50
CROWN OF SILVER, see QUARTZ (Psilomelane Chalcedony)
CUPRITE
Very rarely, as small clear crystals suitable for faceting collectors’ gems; the term “cuprite” is commonly used to designate a cuprite-stained epidote metarhyo-lite from Pennsylvania which has some use in cabochons and ornamental objects.

BAYLDONITE
Bright chartreuse-green masses occasionally from the copper mines near Tsumeb, S. W. Africa, in cabochon grade; rare; collectors’ gem only.
BENITOITE
Only known source of facet-grade crystals is at Dallas Gem Mine, San Benito County, California; rarely available except in small fragments seldom over 2-3 ct.; relatively soft; collectors’ item. Largest gem known 9 ct.; cut gems under i /2 ct. common; over 1 ct. rare and over 3 ct. extremely rare. Usually blue but a very few crystals have provided colorless faceted gems.
BERYL
Standard commercial gemstone; hard, durable, colorful; provides fine jew¬elry gems and small carvings. By far most expensive variety is emerald, ranking ibove diamond in large richly-colored examples; blue aquamarine highly prized but traces of green drastically reduce value (however, some rich yellow-green aquamarines are heat-treatable to fine blue); golden beryl and morganite only moderately valued, goshenite very low value. Most apricot- or peach-colored beryls, commonly called morganite, fade to pink upon exposure to strong light, the final hue depending on richness of original hue. Aquamarine sometimes contains plate-like brown inclusions capable of creating weak to moderately 5trong stars; catseyes occur in practically all varieties. Largest clean rough pro¬vided by aquamarine, sometimes in crystals of many pounds weight; also large clean crystals in golden beryl, more rarely in morganite and goshenite. Emerald crystals rarely clean when over 1/4″ diameter, but reasonably clean crystals of nearly 1″ diameter have been found.
AQUAMARINE
Supplied almost exclusively by Brazil; also from Madagascar, and sometimes from scattered  deposits  in   the  United  States  and  Australia;   occasionally  in
gem gravels of Ceylon and Burma. Finest blue grade, absolutely without trace of greenish tinge, is sometimes called “Fortaleza” after source in Brazil. Price; drop rapidly with smaller rough and as greenish tinges enter.
EMERALD
Principally from Colombia; also small crystals from Brazil, India, Rhodesia, the last of deep color and suitable for small cut gems; prices ascend steeply according to size and color, the prized color being a deep bluish-green or “Muzo” color, also deerj vellow-ereen  CSandawana. Rhodesial.
SYNTHETIC  EMERALD
Deep to medium green crystals grown by hydrothermal and flux-fusion meth¬
ods; virtually indistinguishable from natural emeralds except through careful
testing; growth methods are costly and slow, resulting in sustained high prices.
GOLDEN   BERYL   (HELIODOR)
Ranks low commercially because the color is not greatly favored for jewelry and resembles that of citrine; large color variations from greenish-yellow to golden yellow to pale yellow; a yellow with a reddish cast is more highly prized. A deep yellow kind has been called heliodor. Principally from Brazil;
GOSHENITE
This colorless variety is cut mainly for collectors;    it is not used commercially.

GREEN   BERYLS
This varietal name embraces deeper-hued green    beryls, ranging from char¬
treuse to somewhat brownish-green types, some of    which are capable of heat
treatment to blue. Paler kinds are generally classed under aquamarine.
MORGANITE
Includes true pink, also peach, apricot, and other orange tints which fade to pink or can be heat-treated to pink; occasionally available in flawless rough large enough to cut gems over 100 ct.; veil-type inclusions common. Ranks low commercially because most cut gems are too pale; the finest pinks occur in Madagascar.
STAR  BERYL
Aquamarine containing numerous very small plate-like crystals of brown hematite parallel to the basal plane and furnishing weak to good stars when properly cut; not all specimens produce stars; rare.

BERYLLONITE
An excessively rare phosphate mineral obtained only from one deposit in Maine as cleavable colorless crystals and fragments up to 2″ diameter; soft, brittle; suitable only for collectors’ gems. Cut gems over 5 ct. very rare.

BINGHAMITE, See QUARTZ BLOODSTONE, See QUARTZ BORACITE
Only from saline deposits of Germany as very pale bluish-green  corroded
crystals not over 3/8″ diameter which provide attractive facet gems;  very rare; collectors’ gem only.

BORNITE
Known as “peacock ore” because of iridescent tarnish film which quickly de¬
velops on fracture and cabochon surfaces; soft, brittle; collectors’ item only.

BOWENITE, See SERPENTINE BRAZILIANITE
Soft, cleavable phosphate mineral in greenish or pale yellow to rich yellow crystals; only from Brazil in cuttable specimens; collectors’ item; largest gems 20-30 ct.
BREITHAUPTITE
A sulfide mineral furnishing brilliant metallic luster cabochons, soft;  COIICM tors’ gem only.

BRONZITE, See HYPERSTHENE BROOKITE
Very small crystals very rarely clean enough to facet; not commercially avail¬able.
BYTOWNITE, see FELDSPAR CACOXENITE, See QUARTZ CALCITE
Clean crystals provide faceted gems of interest only to the collector; some purplish-pink massive material of considerable translucency has also been faceted; much massive, banded calcite is employed in ornaments ranging from wall panelling, counter tops, and pedestals, to book ends, desk stands, and spheres; such material is commonly called calcite onyx; brownish types, usually obtained from cave deposits, are called cave onyx; some onyxes are available in blocks of several tons weight; chatoyant material is called satin spar.

ABALONE, See SHELL
ABALONE PEARL, see PEARL in Chapter VII
ACHROITE, see TOURMALINE
ACTINOLITE (see also NEPHRITE)
Rarely in small crystals; hard but easily cleaved; collectors’ gem only.
Madagascar, small dark green crystals, 1/4
AGATE, See QUARTZ ALABASTER, See GYPSUM ALBITE, See FELDSPAR ALEXANDRITE, See CHRYSOBERYL ALGAE, See QUARTZ ALGODONITE
Irregular masses from Michigan copper mines furnish unusual cabochons of metallic luster; rare; collectors’ gem only.

ALMANDITE, See GARNET AMAZONITE, See FELDSPAR AMBER
Mostly supplied by East Germany and Denmark in pieces to 4″ diameter; Burmese and Italian amber rarely available; Dominican amber commonly offered but seldom of good lapidary grade; avoid recent fossil resin copal which is much cheaper than true amber but also crazes quickly and has no place in the lapidary arts.
AMBERDAN
Tests indicate that this is not amber but a suitably colored plastic material closely resembling true Baltic amber in appearance; sold in rectangular blocks.
AMBLYGONITE
Almost colorless to pale straw-yellow to rich yellow cleavage masses from Brazil affording clear areas suitable for faceting; supplies sporadic; soft; rare; collectors’ gem only. Usual size faceted gems 3-15 ct.; record gem of about 70 ct. known.
AMETHYST, see QUARTZ ANALCIME
A common mineral but very rare in transparent crystals sufficiently large to
cut small faceted gems not over 1-2 ct.; soft, fragile; collectors’ gem only.

ANDALUSITE
The clear variety provides beautiful dichroic gems in green-red or brown-red when properly cut; hard, durable, but too rare to be more than collectors’ gems; supplied mainly from Brazil, also Ceylon, as waterworn pebbles and crystals; veil inclusions common; usual size 1/2″, rarely to 100 ct.; cut gems to 5 ct. common but cut gems to 20 ct. rare and valuable.
CHIASTOLITE
Impure variety of andalusite in the form of cigar-shaped crystals to 1″ diam¬eter and displaying black cross-like figures against a white to tan background; soft; sometimes cut as a curiosity.
ANDRADITE, See GARNET ANGLESITE
Extremely soft and fragile lead mineral; rarely in clear crystals large enough to facet; colorless to pale brown; collectors’ gems.
ANTHOPHYLLITE
Sometimes displays a bronze iridescence but rarely available and seldom cut.
ANTHRACITE
Selected masses from Pennsylvania are suitable for carvings and ornamental items but seldom offered and then only at pound prices.
APACHE TEARS, See OBSIDIAN APATITE
Popular among amateur cutters, but soft and requiring care in treatment; abundant vivid yellow crystals from Mexico yielding gems to 20 ct.; small frac-
ture fragments of green and yellow-green available from other sources; Maine purple and Burma blue rare and highly prized; Mexican yellows can be heat-treated to colorless; greenish catseye available from Brazil; collectors’ gem only.
AQUAMARINE, See BERYL ARAGONITE
Rarely in facet-grade crystals only from Bilin, Czechoslovakia, as elongated pale straw-yellow prisms capable of cutting gems to 8 ct.; soft, fragile; collectors’ gem only. Massive material sometimes offered for cabochons but most of this is actually calcite.

ARGILLITE
Soft gray slate-like rock from British Columbia used for carvings but under Indian monopoly and not usually sold.
AUGELITE
Soft, fragile; clear colorless crystals only from Champion Mine, Mono County, California; now unobtainable; collectors’ gem only.
AVENTURINE, See FELDSPAR or QUARTZ AXINITE
Recently in large quantities from Baja California, Mexico, as brown crystals yielding faceted gems to 23 ct.; strongly trichroic; intensity of color makes gems larger than about 5 ct. appear dark; while classed as a collectors’ gem the hardness and durability is sufficient for normal wear in jewelry but the color is commercially undesirable.
AZURITE
Small clean crystals facetable but finished gems must not be over i/88 thick if any light is to be reflected; soft, fragile; collectors’ gem only. Attractive cabochon material sometimes available but most material offered is too porous to permit good polish; alternate bands of azurite and malachite, sometimes AZURMALACHITE, See AZURITE BARITE
Very soft and fragile crystals provide small faceted gems for collectors; com¬monly available from South Dakota, Colorado, and England; massive barite rarely available.

ROUGH GEMSTONE PRICES
Rough gemstones, including certain organic materials, but not pearls, are listed alphabetically with cross references for varieties. Each entry is preceded by appropriate statements of characteristics, sizes, qualities, sources, etc. Not all varieties are included because so many of them, espe¬cially among the numerous members of the quartz family, are no more than trivial sub-varieties of little economic importance. Continue Reading »