Lets Talk Gemstones

By Edna B. Anthony, Gemologist
(Contact the author for permission to reproduce this article in any form.)
P.O.# 62653; COLORADO SPRINGS, CO. 80962
E-MAIL eba@bwn.net

BERYL (A CYCLOSILICATE)

GOSHENITE (COLORLESS BERYL)

Goshenite is the transparent, colorless, alkali-bearing pure beryl that was discovered in Goshen, Hampshire County, Massachusetts. The Lily Pond mine in a pegmatite near a small lake was the source of crystals accompanied by other pale greenish-blue, bluish-green, yellowish, pink, and white beryl crystals. Dr. John Sinkankas tells us that originally the designation included "pink beryls" and "pale-colored beryls." The name is now applied to transparent colorless beryls and often includes nearly colorless aquamarine, where the blue tones are undetected. "Lucid" and "white" beryl are terms frequently used by members of the jewelry industry to describe morganite. No trace elements are present in the chemical make-up of goshenite to impart color.
Low dispersion (0.014) may contribute to the infrequent use of goshenite as a desired gem, despite its excellent hardness, toughness, and resistance to corrosive substances. Since the 1st century A.D., the good qualities of colorless beryl have made it an ideal substitute for other colorless gemstones. Silver or green foil is sometimes placed behind the faceted colorless beryl and mounted in a "closed" setting to create imitations of diamonds and emeralds. Doublets and triplets constructed by "sandwiching" sections with colored cement or a thin slice of a synthetic or natural gemstone are used to simulate other valuable gems. The slice of natural gemstone could contain inclusions specific to the imitated gem. Bezel mounts hide the junctures at the girdles of such creations and make the substitution difficult to detect.

Beryl occurs in such quantities of large and often flawless crystals that inclusions in goshenite used for gem purposes are seldom tolerated. Goshenite is found worldwide, but significant deposits lie in various locations in the former U.S.S.R., Mexico, Brazil, and Canada. California, Colorado, Utah, Idaho, South Dakota, North Carolina, Maine, Connecticut, and New Hampshire are all sources of goshenite in the United States.


 
Gemstone Properties
SPECIE
aquamarine
Composition:
beryllium aluminum silicate
Be 3 Al 2 Si 6 O 18
Class:
silicate; cyclosilicate
Group
beryl
Species:
goshenite
Crystal System:
hexagonal per Arem; hexagonal (trigonal) per Schumann
Variety:
Colors:
colorless
Phenomena:
none
Streak:
white
Diaphaneity:
transparent, translucent to opaque
Habit:
prismatic
Cleavage:
imperfect; none
Fracture:
conchoidal
Fracture Lustre:
vitreous 
Lustre:
vitreous
Specific Gravity
varies from 2.60 to 2.90
Hardness
7.50 to 8.0
Toughness:
very good; can be brittle
Refractive Index
o=1.566 to 1.602; e= 1.562 to 1.594
Birefringence:
varies from 0.004 to 0.008
Optic Character
uniaxial negative
Dispersion:
0.014
Pleochroism
none
Ultraviolet 
Fluorescence
none
Spectra
not usable
Color Filter
no information
Aqua Filter
no reaction; green indicates nearly colorless aquamarine
Chelsea Filter
no information
Solubility
insoluble in acids except in fluoric acid
Thermal Traits
avoid thermal shock; remove stone during jewelry repairs
Treatments
none
Inclusions
no specific references to inclusions in goshenite were found