The following thin sections are to be used as
reference samples to help you get acquainted with the various minerals in thin
section: You should spend some time with these before you proceed further with
this lab exercise.
X-2 Grit. This is the grit or abrasive that is used in the preparation of thin sections. It is a contaminant and not a part of the sample. You must learn how to recognize it, but just disregard it when you see it.
X-3 Lint: This is cloth fiber or lint. It is also an contaminant. Just disregard it when you see it.
1 Quartz. The quartz, variety chert. A very typical example for chert.
99 Cu 2 Gypsum. This thin section is mostly the mineral gypsum. It occurs here in two forms (1) small almost cryptocrystalline form and (2) as large euhedral to subhedral crystals. The thin section is think. The fine grayish material is probably clay. View under crossed polarized light (CPL).
01-KY-01 Calcite and dolomite. Sample has been stained with Alizarin Red-s and Potassium Ferricyanide Blue. It contains ferroan calcite, ferroan dolomite, and non-ferroan dolomite. View in plain polarized light (PPL) for best results.
CH-1 Calcite. Sample has been stained with Alizarin Red-s and Potassium Ferricyanide Blue. It is almost entirely non-ferroan calcite.
Wh Quartz. Really poor thin section but look at the effect of varying thickness on the appearance of quartz in polarized light. Can you relate thin section thickness to the colors you see?
1059 Quartz and calcite. Mostly big quartz grains with a small amount of calcite between the grains. View in polarized light and the calcite shows up as third and forth order colors and the quarts as first order colors.
1098 Phosphorite.
1063 Calcite and quartz. Mostly calcite but on the end toward the paper label there is a patch of quartz, variety chert
1037 Calcite. This thin section is to thin.
CP 570 Calcite and porosity. Calcite is unstained. Pore space filled with blue epoxy.
CAM 1 Siderite
CAM 2 Siderite, chlorite, ferroan calcite, quartz, limonite. Sample has been stained with Alizarin Red-s and Potassium Ferricyanide Blue. Most of the sample is siderite. Chlorite is yellowish in plain light and first order grays in polarized light. Ferroan calcite is purple in plain light. Limonite is red brown in plain light. Quartz is clear in plain light and first order white to dark gray in polarized light.
CAM 3 Sideite, chlorite, ferroan dolomite, and quartz. Sample has been stained with Alizarin Red-s and Potassium Ferricyanide Blue. Most of the sample is siderite. Chlorite is slightly greenish in plain light, first order gray in polarized light. Ferroan dolomite is Carolina blue in plain light.
DBQ Calcite, dolomite, tiny amount
of quartz. Thin section has been stained
with Alizarin Red-s.
I-S-8'2 Calcite and quartz. Thin section has been stained with Alizarin Red-s. Calcite reddish. Quartz small clear grains.
SP-247 Dolomite. Thin section has not been stained.
CP 805 Dolomite and quartz. Thin section has been stained with Alizarin Red-s and Potassium Ferricyanide Blue. Mostly ferroan dolomite, the Carolina blue. Quartz is the tiny clear grains.
1004 Calcite, quartz, glauconite, and phosphorite. Unstained thin section. Calcite dominates thin section. Quartz occurs as small sub rounded to angular grains that are clear in plain light and first order grays under polarized light. Glauconite in green in plain light. Phosphorite is clear in plain light and black under crossed polarizers.
OM-608 Anhydrite almost entirely.
1132 Calcite, aragonite, quartz, feldspar, glauconite. Unstained thin section. Mostly quartz grains but a few feldspars are in there. Calcite is the cement between the grains of quartz. Green grains are the glauconite. the big feathery looking grains are aragonite sea shells.
Schist Quartz and muscovite. Thin section of schist. Mostly quartz but the tiny blade like crystals is muscovite (white mica).
Gneiss Quartz, feldspars, muscovite, biotite. Thin section of gneiss. Mostly quartz but look for the feldspars (cleavage, twinning, etc.!). Muscovite (white mica) is nearly whit in plain light first and second order pretty colors in polarized light. Biotite is yellowish orange to brown and pleochroic in plain light.
Beadle Mine Dump #5 Dolomite, pyrite, sphalerite. Most of the sample is dolomite. The opaque material is the pyrite or maybe marcasite, check it out with reflected light. The brown in plain light and black in polarized light is the sphalerite. May also be a bit of quartz in the rock.
TS74-4-2 Quartz, glauconite, dolomite, calcite. Quartz is the clear grains in plain light and first order gray to second order yellows in polarized light but there are probably a few feldspar grains in there also. Glauconite is the conspicuous green grains. The yellowish material between the grains and patches through out the sample are dolomite. There is also some calcite, good luck telling it from the dolomite but you can if you are good!!! Look at the quartz in polarized light and see the effect of a thin section having a varying thickness.
SPM-1 Calcite, quartz. Thin section has been one half stained with Alizarin Red-s. It is also a bit thick. Look to the few quartz grains to verify this.
BARITE Barite.
H4884m Dolomite, anhydrite. Mostly dolomite but a little anhydrite.
H4863m Dolomite, anhydrite. This thin section has been cut way thin.
D8504 Quartz. Nice clean quartz grains with a few minor other items.
21-3 Quartz. Mostly quartz grains but most have stressed crystal lattices hence the sweeping extinction.
SP822 Calcite, quartz, phosphorite, galuconite. How thick is this thin section?
Select one of the envelopes A, B, C, D, E, F, or G for exercise 2, 3, and 4. Record the letter with your data.