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Index (R)
RA - RC
RD - RF
RG - RJ
RK - RN
RO - RR
RS - RV
RW - RZ
Moment of truth
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The Sun, with a diameter of 1,392,000 km, is made of 94% hydrogen atoms. |
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A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W
X
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RS - RV
ruby Min.
A very rare mineral corundum (Al2O3) that appear transparent pink to red due to the presence of traces of chromium. Gem-quality ruby can be mined in Mogok, Burma, Thailand, Sri-Lanke and Afghanistan, where it is found in
metamorphic rocks. Natural ruby is used in jewelry, while industrially produced synthetic ruby (Verneuil flame-fusion process) is used in laser applications and watches. Due to its rarity, fine ruby is more expensive than diamond. The most expensive
variety being the Mogok Ruby, a 15.97 carat untreated (unheated) ruby sold for over 3.6 million US dollar in 1988.
rutile Min.
A mineral form of titanium oxide, TiO2, which is the chief ore of titanium. It appears black or reddish brown in large crystals or golden yellow when growed as thin crystals.
Tiny inclusion of rutile in ruby gives interesting star light effects (asterism).
RS - RV
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W
X
Y
Z
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