Specimen: 2014-078-1
This sample is a marble with a significant range in grain size and a somewhat diverse chemical composition. The texture is mostly granoblastic with foliated masses of accessory minerals and some larger porphyroblastic carbonate, quartz and feldspar grains. Maximum carbonate grain size is about 1.7 mm, minimum is .1 mm, and the modal size is .5 to .25 mm. Grain boundaries are mostly curved or straight with a lesser amount of sutured boundaries. Twin lamellae in carbonates are common. Non-carbonate accessory minerals minimally include quartz, feldspar (albite twinning), micas (muscovite, phlogopite and others?), sillimanite, opaques, sphene, and unidentified low birefringence minerals (brucite?). The most common are individual and small aggregates of quartz, many reflecting strain induced nucleation. Maximum quartz crystal size is around .5 mm. Feldspar porphyroblasts have a maximum size of 1.2 mm. Most other accessory minerals are present in fine grained semi-foliated ground masses. The small size of most crystals precludes definitive identification of all minerals, but micas predominate. All non-carbonate accessory minerals constitute about 30 to 40 percent of slide area. Preferred orientations of mineral elongation and the morphology of accessory mineral aggregates produces a banding in the thin section. Diffuse banding is also visible in the hand sample. There is no weathering apparent in this sample other than the possible formation of brucite and related alteration in the foliated masses.
MP 9/4/2015

Specimen: 2014-078-2
This sample is a relatively coarse grained marble. The texture is overall granoblastic with random grain orientation. Maximum carbonate grain size is around 1.8 mm, minimum is .1 mm, the modal size is a wide range between 1.3 to .6 mm. Grain boundaries are mostly curved, or straight, with a lesser number of sutured boundaries. Twinning lamellae in carbonates are common. The most common non-carbonate accessory minerals are of quartz that occur as individual crystals and as aggregates. Aggregates reflect significant stress induced nucleation and larger quartz grains present wave extinction. Individual quartz grains have a maximum dimension of 1.4 mm; most are significantly smaller. Other non-carbonate accessory minerals include micas (muscovite, phlogopite?), sillimanite, sphene, opaques, and low birefringence minerals that cannot be conclusively identified. Most of these minerals occur in foliated masses. All non-carbonate accessory minerals constitute about 30 to 40 percent of slide area. The distribution of accessory mineral aggregates produces a somewhat foliated appearance in thin section. Diffuse banding and clouding are also visible in the hand sample. There is no appreciable weathering visible in the thin section other than the possible formation of brucite and related products in the foliated masses.
MP 9/4/2015