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Masslite Quarry, Plainville, Norfolk Co., Massachusetts, USA

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Location is approximate, estimate based on other nearby localities.
Latitude & Longitude (WGS84): 42° North , 71° West (est.)
Margin of Error:~39km
Locality type:Quarry
Köppen climate type:Dfa : Hot-summer humid continental climate

A slate and concrete aggregate quarry located about 1 1/4 mile NW of Plainville. Started about 1935. Workings were 700 feet long by 60 feet wide and 40 feet deep (or high at the face). Mostly a location for Carboniferous (Westphalian C) plant fossils and trackways. Many undetermined sulphates are found in a thick coal seam.

There are multiple levels, and the level searched is crucial as to which type of fossils will be found. The level that is at about the same elevation as the entrance contains white plant imprints on dark gray rock. These rocks are not hard to find but are definitely the minority, and are found in the rock piles leaning against the quarry wall at the opposite side of the entrance. White strip-like calamites leaves are very prevalent and are often exposed, a perfect flag for a fruitful rock worth splitting. Directly above this plant area, but at the top level, there are light gray or light brown (oxidized surface?) rocks that contain rather small footprints of reptiles and amphibians. These rocks are also in a pile leaning against the quarry wall, but unlike the plant rocks, are the only type present. Most levels, especially all those beside the top one, contain interesting quartz crystals as well as other inorganic minerals.

Plants and footprints are the most common fossils found, but insects among others have been reported. The plant fossils are especially interesting because the rock is fairly highly metamorphosed, causing the plants to be white and the rocks to often contain graphite or quartz crystals. The footprints are in more standard sedimentary rock and are often somewhat difficult to discern. One must remember that this quarry is still actively mined, so it is off limits except for Sundays and likely holidays. The walls are sheer and rocks can fall, so keep a safe distance from them.

Select Mineral List Type

Standard Detailed Strunz Dana Chemical Elements

Mineral List

9 valid minerals.

Rock Types Recorded

Note: this is a very new system on and data is currently VERY limited. Please bear with us while we work towards adding this information!

Select Rock List Type

Alphabetical List Tree Diagram

Detailed Mineral List:

Reference: No reference listed
Formula: CaCO3
Reference: Rocks & Min.: 21:754.; Michael W. Kieron collection
Formula: Mg5Al(AlSi3O10)(OH)8
Reference: Michael W. Kieron collection
Reference: No reference listed
Formula: C
Reference: Rocks & Min.: 21:754.
Formula: CaSO4 · 2H2O
Reference: P Cristofono collection
Gypsum var: Selenite
Formula: CaSO4 · 2H2O
Reference: P Cristofono collection
Formula: (Fe,O,OH,H2O)
Formula: FeS2
Reference: Rocks & Min.: 21:754.; Michael W. Kieron collection
Formula: SiO2
Reference: Michael W. Kieron collection
Formula: FeCO3
Reference: Kenneth Gliesman
Sulphur ?
Formula: S8
Reference: Michael W. Kieron collection
Formula: ☐{Ca2}{Mg5}(Si8O22)(OH)2
Reference: Michael W. Kieron collection

List of minerals arranged by Strunz 10th Edition classification

Group 1 - Elements
Sulphur ?1.CC.05S8
Group 2 - Sulphides and Sulfosalts
Group 4 - Oxides and Hydroxides
Group 5 - Nitrates and Carbonates
Group 7 - Sulphates, Chromates, Molybdates and Tungstates
'Gypsum'7.CD.40CaSO4 · 2H2O
var: Selenite7.CD.40CaSO4 · 2H2O
Group 9 - Silicates
Unclassified Minerals, Rocks, etc.

List of minerals arranged by Dana 8th Edition classification

Semi-metals and non-metals
Sulphur ?
Group 2 - SULFIDES
AmBnXp, with (m+n):p = 1:2
Gypsum29.6.3.1CaSO4 · 2H2O
Group 66 - INOSILICATES Double-Width,Unbranched Chains,(W=2)
Amphiboles - Mg-Fe-Mn-Li subgroup
Group 71 - PHYLLOSILICATES Sheets of Six-Membered Rings
Sheets of 6-membered rings interlayered 1:1, 2:1, and octahedra
Group 75 - TECTOSILICATES Si Tetrahedral Frameworks
Si Tetrahedral Frameworks - SiO2 with [4] coordinated Si
Unclassified Minerals, Rocks, etc.
var: Selenite
-CaSO4 · 2H2O

List of minerals for each chemical element

H ClinochloreMg5Al(AlSi3O10)(OH)8
H GypsumCaSO4 · 2H2O
H Limonite(Fe,O,OH,H2O)
H Gypsum (var: Selenite)CaSO4 · 2H2O
H Tremolite☐{Ca2}{Mg5}(Si8O22)(OH)2
C CalciteCaCO3
C GraphiteC
C SideriteFeCO3
O CalciteCaCO3
O ClinochloreMg5Al(AlSi3O10)(OH)8
O GypsumCaSO4 · 2H2O
O Limonite(Fe,O,OH,H2O)
O QuartzSiO2
O Gypsum (var: Selenite)CaSO4 · 2H2O
O SideriteFeCO3
O Tremolite☐{Ca2}{Mg5}(Si8O22)(OH)2
Mg ClinochloreMg5Al(AlSi3O10)(OH)8
Mg Tremolite☐{Ca2}{Mg5}(Si8O22)(OH)2
Al ClinochloreMg5Al(AlSi3O10)(OH)8
Si ClinochloreMg5Al(AlSi3O10)(OH)8
Si QuartzSiO2
Si Tremolite☐{Ca2}{Mg5}(Si8O22)(OH)2
S GypsumCaSO4 · 2H2O
S PyriteFeS2
S Gypsum (var: Selenite)CaSO4 · 2H2O
S SulphurS8
Ca CalciteCaCO3
Ca GypsumCaSO4 · 2H2O
Ca Gypsum (var: Selenite)CaSO4 · 2H2O
Ca Tremolite☐{Ca2}{Mg5}(Si8O22)(OH)2
Fe Limonite(Fe,O,OH,H2O)
Fe PyriteFeS2
Fe SideriteFeCO3


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- Rocks & Minerals: 21: 754.

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