Chapter M

Madeira topaz: 29
Mason County: 20, 22, 23, 26, 29, 30, 39, 40
Massachusetts: 29
Maverick County: 18
microcline: 20, 21, 23-24, 29, 37
Mohs scale of hardness: 6
moonstone: 28
Mount Bonnell: 19
muscovite: 23

N
natural glass: 18, 24, 28
Needle Peak, Presidio County: 27
nivenite: 21
Nolan County: 19
Nueces River: 25

O
obsidian: 24, 29
Oklahoma: 29
opal: 20, 24
opalized wood: 35
orbicular jasper: 28
ounce: 7

P
Packsaddle Mountain: 23
Packsaddle schist: 30
palm wood: 21, 35
Palo Duro Canyon: 21
pavilion: 13, 16
facets: 16
girdle facets: 16, 17
pearl: 24-25
pegmatites and/or pegmatite dikes: 18, 20, 21, 22, 23, 26, 29, 39
petrified wood: 26
phantom crystals: 26
pistacite: 20
pleochroism: 5
point: 7
polishing: 17
lap: 13, 16
preformed stone: 16
preforming: 15
Presidio County: 20, 22, 24, 25, 26, 27, 28
properties of gemstones: 5-7

Q
quartz: 20, 21, 23, 25-28, 29, 30
smoky: 38

R
radioactive elements: 22
radioactivity of gadolinite: 21
rarity: 6
Reeves County: 26, 27
Rio Grande: 25
gravels of: 21, 27, 38
Valley: 27
rock crystal: 26
rose quartz: 26

S
Sabine River: 25
sanding: 12
sanidine: 28
sawing: 10
scheelite: 20
schorl: 30
size: 7
“skill” facets: 16
“slab” of gem materials: 11
Smithsonian Institution: 21
smoky quartz: 23, 26, 37
smoky topaz: 29
Spanish topaz: 29
specific gravity: 7
spinel: 18, 28
star facets: 17
step cut: 15
streak: 6
synthetic gems: 7

T
table facet: 13, 15
tektite (bediasite): 28-29, 39
tenacity: 6
thorogummite: 21
topaz: 23, 26, 29-30, 39, 40
quartz: 29
tourmaline: 26, 29, 30-31, 40
Town Mountain, Llano County: 26, 30
transparency: 6
Travis County: 19, 35
Trinity River: 25
tumbled gems: 17
turquoise: 31

U
U. S. National Museum: 30