BETA

Danby Gray

Submitted by Ed FitzGerald on Mon, 2014-11-24 10:38
Trade Name Alias: 
Stone Type (Commercial): 
Description: 

Gray in color with a mix of the white Danby background. One of the older Danby grades utilized and has a long history of use throughout North America.

Availability: 
Available
Physical Data
Absorption (%): 
0.06
Density (lb/cf): 
169.20
Flexural Strength, Dry (psi): 
1,226
Modulus of Rupture, Dry (psi): 
1,077
Compressive Strength, Dry (psi): 
9,475
Bulk Specific Gravity: 
2.71
Abrasion Resistance: 
12.10
Geology
Stone Type (Lithologic): 
Grain Shape: 
Angular
Grain Size: 
Coarse
Medium
Petrographic Description: 

Specimen: 2014-071-1
This sample is a relatively coarse grained marble. The texture is overall granoblastic with random grain orientation. Maximum carbonate grain size is around 2 mm, minimum is .1 mm, the modal size is .5 to 1.25 mm. Grain boundaries are mostly curved or straight with a lesser amount of sutured boundaries. Twinning lamellae in carbonates are common. Indistinguishable quartz and feldspars are the most common non-carbonate accessory minerals, occurring as both isolated grains and in small aggregates. Individual quartz grains have a maximum dimension of .35 mm, most are smaller. Aggregates of likely pure quartz have a maximum dimension near 1.1. Many of these small aggregates appear to be the result of the recrystallization of quartz in response to stress; only a few quartz grains present wave extinction. Feldspars were only definitively identified in a few instances where albite twinning was observable. These always occurred in clusters with mica (phlogopite, muscovite?) minerals. Quartz/feldspar in these aggregates was very fine grained with modal sizes near .04 mm. Due to the small size of crystals it is likely other low birefringence minerals are also present but indistinguishable. Rare opaque minerals of a similar size also occur in these aggregates. All non-carbonate accessory minerals constitute about 15 percent of slide area. Quartz, feldspar, mica, opaque bearing aggregates occurred in only a local region of the slide and show some preferred orientation, producing banding. Some diffuse banding is also visible in the hand sample. There is no appreciable weathering in this sample.
MP 9/4/15

Specimen: 2014-071-2
This sample is a relatively coarse grained marble. The texture is overall granoblastic with random grain orientation. Maximum carbonate grain size is around 2 mm, minimum is .1 mm, the modal size is .75 to 1.5 mm. Grain boundaries are mostly curved or straight with a lesser amount of sutured boundaries. Twinning lamellae in carbonates are common. Indistinguishable quartz and feldspars are the most common non-carbonate accessory minerals, occurring as both isolated grains and in aggregates. Individual quartz grains have a maximum dimension of .4 mm, most are smaller. Aggregates of likely pure quartz have a combined maximum dimension near 1.2. Many of these aggregates appear to be the result of the recrystallization of quartz in response to stress; relatively few quartz grains present wave extinction. Feldspars were only definitively identified in a few instances where albite twinning was observable. These always occurred in clusters with mica (phlogopite, muscovite?) minerals. Quartz/feldspar in these aggregates was very fine grained with modal sizes around .03 to .07 mm. Due to the small size of crystals it is likely other low birefringence minerals are also present but indistinguishable. Opaque minerals of a similar size also occur in these aggregates. Opaques also rarely occur as individual grains with a maximum size of .5 mm. An extremely high refractive index material present in low quantities is likely titanite; aggregates of this mineral reach .5 mm. Quartz, feldspar, mica, titanite, opaque bearing aggregates occurred in a localized region of the slide and show preferred orientation, producing banding. The maximum width of these bands reached 3 mm. All non-carbonate accessory minerals constitute about 20 percent of slide area. In this slide this total is approximately equally divided between diffuse quartz and the concentrated areas of multi-mineral aggregates. Some diffuse banding is also visible in the hand sample. There is no appreciable weathering in this sample.

Images

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Specimen ID
2014-071-1 Image of specimen in dry conditions. Finish: Polisheddownload image
2014-071-2 Image of specimen in dry conditions. Finish: Honeddownload image

Thin Sections

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Specimen ID Non-polarized Cross-polarized
2014-071-1 Specimen shown in non-polarized light.download image Specimen shown in cross-polarized light.download image
2014-071-2 Specimen shown in non-polarized light.download image Specimen shown in cross-polarized light.download image

Quarry

No quarry information available for this stone.

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