Browse Items (264 total)

Taxonomy Phylum: Brachiopoda Diagnostic features Two valves (brachial and pedicle) Bilateral symmetry Growth lines Adductor and ductor muscle scars Pedicle Commissure Gape Teeth and socket (articulates; no teeth or socket in…

Formula CaCO3 Structure Non-silicate Crystal System Crystal system: trigonal (-) Physical Properties Colour in hand specimen: whiteCleavage: rhombohedralHardness: 3 Optical Properties Colour in plane polarised…

See simple twins.

Formula (Mg,Fe2+,Fe3+,Mn,Al)12[(Si,Al)8O20](OH)16 Structure Sheet silicate Crystal System Crystal system: monoclinic (+) (-) Physical Properties Colour in hand specimen: green Cleavage: one, good Hardness: 2-3 Optical…

Formula (Ca,Mg,Fe2+,Fe3+,Ti,Al)2[(Si,Al)2O6] Structure Chain silicate Crystal System Crystal system: monoclinic (+) Physical Properties Colour in hand specimen: black Cleavage: two at 90° Hardness: 5.5-6 Optical Properties Colour in…

Have a look at the rhyolite glass (L113), the flint nodule (L370), and quartz (M411) in the 1A Reference Series.

Taxonomy Phylum: Cnidaria Class: Anthozoa Diagnostic features Radial or biradial symmetry External skeleton Septa Tabulae Stratigraphic range Ordovician to present Tabulate, rugose: Ordovician to Permian (extinct at P/T extinction) Scleractinian:…