GARNET Mn3 Al2 Si3 O12 to Fe3 Al2 Si3 O12
Crystal Description: Cubic
Usually occur as either smooth, dark red gemmy trapezohedral
crystals, sometimes modified by the dodecahedral form; rarely occur
as octahedral crystals or highly modified clinkers made up basically of
garnet intergrown with either rhyolite and/or quartz. Also occurs as
hematite pseudomorphs replacing garnet. Often the garnets consist of
a thin, altered rind on the outside and pure garnet in the center. Most
are under 0.5” (12mm) in diameter, but may form crystals exceeding
2.5” (6.5cm) in diameter; the largest gemmy crystal found was 2.2”
(5.5cm) in diameter. Crystals may form as single crystals or as clusters
consisting of several dozen individual crystals.
Physical Properties:
Color- Red to dark brown (black if altered)
Luster- Glassy to dull
Hardness- 6 – 7.5
Specific Gravity- 3.5
Garnets are also another mineral of interest to collectors. They
occur throughout the Thomas Range in isolated areas. They also occur
in two distinct types. Type I consists of euhedral crystals, with the
most common forms being the basic trapezohedron, sometimes modi-
fied by the dodecahedron. Crystals seldom exceed 1/2 inch in diam-
eter, although some crystals exceeding two inches in diameter have
been found.
In color, they vary from brown to a deep cinnamon-red color.
They are sometimes well formed, smooth-faced crystals, often of gem
quality. They generally contain minute inclusions of quartz, topaz, and
hematite, and have a sugary texture similar to sand topaz. Since topaz
also occurs in the area, it is not uncommon to find good combinations
of the two.