124
(Ca,Mg,Fe,Al)2(Si,Al)2O6 — clinopyroxene, monoclinic system, on a lava matrix
Cm 5X4,5X6,5
Cm 5X4,5X6,5
125
Igneous rock (quartz + feldspar) — porphyritic texture; name not verified in geological literature
Cm 4,5X3,5X7
Cm 4,5X3,5X7
126
MnO₂ (pyrolusite/WAD) — oxide films, no distinct crystalline structure
Cm 4X3,5X7
Cm 4X3,5X7
128
An intrusive igneous rock with a granitic composition — porphyritic texture
Cm 4X4X6,5
Cm 4X4X6,5
130
CaCO₃ — calcium carbonate, trigonal system (a polymorph of aragonite)
gr 997 cm 9X7X6
gr 997 cm 9X7X6
131
Rhyolitic volcanic glass (~70% SiO₂) — amorphous, lacking a crystalline structure
gr 923 W. 15 - D. 14 cm
gr 923 W. 15 - D. 14 cm
136
SiO₂ (banded chalcedony) — fibrous microcrystalline structure, trigonal system
W. 18 - D. 15 Cm
W. 18 - D. 15 Cm
142
SiO₂ — trigonal system (polycrystalline aggregate)
W. 8 - D. 9 - H. 4 cm
W. 8 - D. 9 - H. 4 cm
143
Silicon dioxide (SiO₂), a compound of silicon (Si), hydrogen (H), and oxygen (O).
W. 9 Cm
W. 9 Cm
145
Brazil, Ametista do Sul (state of Rio Grande do Sul) (?)
W. 8 - H. 19 cm
W. 8 - H. 19 cm
150
Brazil, Ametista do Sul (state of Rio Grande do Sul) (?)
W. 9 - H. 14 Cm
W. 9 - H. 14 Cm
155
SiO₂ (microcrystalline quartz/chalcedony) — radial spherulitic structure, trigonal system
160
CaSO4·2H2O (gypsum) or BaSO4 (barite) — rosette-shaped crystalline aggregate
Cm 22X15X29
Cm 22X15X29
161
one free-form piece of rose quartz one mixed cluster of quartz, calcite, and chalcopyrite crystals
164
Na₃Ca(Si₃Al₃)O₁₂S (lazurite) + calcite + pyrite — metamorphic rock
W. 13 - H. 2 Cm
W. 13 - H. 2 Cm
169
A mysterious glass-like formation with horizontal layers.
W. 13 - D. 9 Cm
W. 13 - D. 9 Cm
