Chapter M

Macon, James W.: vii
magma: 9
magnesium, source of: 55
magnetite: 28, 67, 70, 72, 85, 87, 93
malachite: 34, 52, 53, 54
Malone Mountains: 65
manganese: 73, 75
map—
geologic: 4-5
physiographic outline: 42
Marathon area: 42, 84, 88
marble: 13, 14, 40, 46, 54, 75
Marble Falls: 62
Marion County: 70
martite: 67
Mason: 74
Mason County: 48, 55, 58, 59, 60, 61, 67, 72, 73, 74, 76, 80, 83,
94
masses, crystalline, definition of: 14
Matagorda County: 91
Mayfield prospect: 74
McCulloch County: 88
Medina County: 45
Menard County: 65
mercury: 8, 49, 50, 51
metamorphic rocks, definition of: 12
metamorphism, definition of: 13, 14
mica (_see also_ biotite; muscovite): 8, 60, 61, 63, 64, 72, 76,
79, 80, 85, 87
mica gneiss and/or schist: 59, 76, 87
Mica Mine area: 58, 76, 77, 79
microcline: 55, 56, 61
milky quartz: 82
Mills County: 49
mineral identification charts: 24
mineralogists: 2
minerals, definition of: 7, 14, 15
Mississippian: 3, 55, 69, 88
Mitchell County: 66
Mohs scale of hardness: 16, 17
molybdenite: 63
montmorillonite: 51
Morris County: 70
moss agate: 84
Moss Bluff salt dome: 91
muriatic acid: 22
muscovite: 31, 32, 34, 37, 38, 76

N
Nacogdoches County: 70
Nash salt dome: 91
native elements: 8
native mercury: 8
native silver: 26, 89
nodule: 19, 44, 49
Nolan County: 20, 49, 63, 64, 65
north-central Texas: 43, 51, 52, 69, 70, 86, 88

O
Oakville strata: 97
obsidian: 40, 77
occurrence of minerals: 14
ocher, red: 67
octahedral cleavage: 56, 57
oil shale: 88
olivine: 88
onyx: 84
öolitic limestone: 69
opal: 21, 29, 30, 31, 35, 37, 38, 78, 86
opaline granite: 72
opalized wood: 20, 78, 84
open-hearth furnace: 70, 72
Orchard salt dome: 91
Ordovician: 3, 55, 69, 84
orthoclase: 55, 61

P
Packsaddle Mountain: 87
Packsaddle Schist: 87
Palangana salt dome: 91, 97
paleontologists: 2
parting of minerals: 17
Pavitte prospect: 53
Pecos County: 9
Pecos River: 65, 74, 75
pegmatite: 41, 55, 56, 58, 76, 77, 79, 81, 94, 95
Baringer Hill: 80
Pennsylvanian: 3, 45, 51, 55, 69, 70, 86, 88
peridotite: 88
period: 2
Permian: 1, 3, 20, 21, 43, 45, 49, 52, 55, 64, 65, 69, 86, 90
Permian basin: 42, 43, 65, 66
petrified wood: 20, 52, 78, 84
petrologists: 2
phenocrysts: 85
physiographic outline map: 42
pitchblende: 28, 95, 97
placer deposits: 60
Plata Verde mine: 90
Polk County: 98
porphyritic rocks: 45, 85
portland cement: 51, 69, 88
Precambrian: 2, 3, 44, 45, 48, 52, 53, 56, 58, 59, 60, 61, 63, 67,
72, 74, 75, 76, 79, 82, 85, 87, 93, 94, 95, 97
precious opal: 78
Presidio County: 45, 49, 57, 60, 62, 67, 77, 78, 84, 85, 90, 97
Presidio mine: 60, 90
properties of minerals: 14
pseudomorphs: 70, 87
pulverulent limestone: 41, 69
pumicite: 97, 98
pyramidal cleavage: 74
pyrite: 19, 26, 60, 70, 80, 87
pyrolusite: 27, 73, 74
pyroxene: 45

Q
quartz: 8, 20, 29, 30, 31, 33, 36, 37, 38, 48, 51, 54, 56, 59, 60,
61, 68, 72, 78, 79, 80,81, 84, 85, 86, 94
agate: 21, 83, 84
amethyst: 37, 82
chalcedony: 16, 21, 45, 78, 81, 83, 86
chert: 19, 40, 81, 84
cryptocrystalline: 81, 84
jasper: 81, 84
milky: 82
onyx: 84
rock crystal: 82
rose: 82, 83
smoky: 82, 83
quartzite: 41, 74, 84, 86
Quaternary: 2, 3, 51, 79, 98
quicksilver (_see also_ mercury): 50
Quitman Mountains: 57, 58, 60, 62, 67, 82, 90

R
radioactivity: 95, 96
Real County: 49, 51
Recent: 2, 3
“red beds”: 52
red ocher: 67
reef limestone: 1, 12
Reeves County: 65, 85, 91
reference books: 24, 39, 100
refraction, double: 46
rhombohedral cleavage: 46, 54
rhyolite: 40, 85
porphyry: 41, 85
Rio Grande: 83, 84, 97
rock—
crystal: 82
gypsum: 40, 65
identification charts: 39
salt: 40, 65
units: 2
rocks, definition of: 8
Rodda, Peter U.: vii
rose quartz: 82, 83
rosettes: 63, 64
Rustler Springs area: 91
rutile: 82

S
salt (_see also_ halite): 40, 65, 66
domes: 43, 58, 64, 66, 91, 97
lakes: 66
rock: 40, 65
Salt Fork of the Brazos River: 43
sand: 41, 58, 72, 85, 91
blast: 86
building: 85
filtering: 86
glass: 85-86
sandstone: 41, 52, 55, 58, 59, 72, 76, 81, 84, 86
Sandy Creek: 60
San Saba County: 70, 88
Santa Anna: 86
satin spar: 64
Satorsky, Cyril: vii
scale, geologic time: 2, 3
scintillation counter: 96
schist: 41, 56, 58, 72, 73, 76, 81, 87, 93
actinolite: 87
graphite: 63, 87
hornblende: 87
mica: 76, 87
talc: 87, 93
schistosity: 87
schorl: 95
Scurry County: 98
sedimentary rocks, definition of: 10
sediments: 8, 11
chemical: 12
selenite gypsum: 63, 64, 76
series: 2
serpentine: 34, 40, 44, 75, 87, 93
serpentinite: 87
Seven Heart Gap: 45
Shafter: 57, 58, 60, 67, 90
Shafter Lake: 83
shale: 12, 13, 19, 40, 45, 70, 87, 88
oil: 88
Shelby, Cader A.: vii
Sheridan prospect: 53
siderite: 70
Sierra Blanca: 58, 67, 82
silicified wood (_see also_ petrified wood): 20
silt: 12, 85
siltstones: 12
silver: 26, 52, 57, 59, 89
glance: 90
horn: 90
minerals: 89
native: 26, 89
Silver Creek: 58
sinter, calcareous: 46
slate: 13
Smith County: 70
smoky quartz: 82, 83
soapstone: 40, 93
soils: 10
Solitario uplift: 42, 88
Sonora: 18
Caverns of: 19
specific gravity: 18, 99
specular hematite: 67
sphalerite: 57
Spiller mine: 74
Spindletop salt dome: 91
Spring Creek: 56
stalactites: 18, 19
stalagmites: 18, 19
Starr County: 84, 98
static metamorphism: 13
Stonewall County: 52
streak or powder of minerals: 17
streak plate: 17, 22
Streeter: 48, 94
striations: 81, 95
strontianite: 49
strontium: 49
sulfur: 29, 30, 31, 32, 34, 36, 81, 90
Sutton County: 18, 19
system: 2

T
talc: 28, 29, 34, 87, 93
schist: 87, 93
Talc Rock: 93
Taylor County: 45, 49, 60
Terlingua area: 46, 47, 49, 50, 65
Tertiary: 2, 3, 9, 21, 45, 49, 51, 52, 56, 57, 60, 70, 77, 78, 79,
83, 84, 85, 86, 90, 97, 98
terrazzo—
chips: 55, 76
floors: 88
tests, chemical (_see_ chemical tests)
thorium: 80
Thrall oil field: 88
time, geologic: 2, 3
tin: 47
topaz: 36, 38, 94
tourmaline: 33, 82, 94
Town Mountain: 95
Trans-Pecos area: 9, 10, 45, 60, 62, 69, 78, 82, 83, 84, 85, 87,
89, 90, 98
trap rock: 45
travertine: 46
Travis County: 20, 45, 46, 49, 68, 69, 70, 88
tremolite: 44, 93
Triassic: 3, 45, 87
Trinity County: 98
tufa, calcareous: 46
twinned crystals: 46, 63
tyuyamunite: 97

U
Upshur County: 70
uranium: 80, 95, 96
minerals: 95
uraninite: 97
uranophane: 31, 95, 97
Uvalde County: 45, 60, 84, 88