Browse Items (264 total)

Taxonomy Phylum: Hemichordata Class: Graptolithina Diagnostic features Stick-shape (often branched) One or both edges may appear serrated Thecae Rhabdosome Stipes Stratigraphic range Cambrian to Carboniferous (Dendroids) Ordovician to Middle Devonian…

Formula CaSO4∙2H20 Structure Non-silicate Crystal System Crystal system: monoclinic (+) Physical Properties Colour in hand specimen: usually white or colourlessCleavage: rhombohedral, one perfect, two distinctHardness: 2 Mineral…

Formula NaCl Structure Non-silicate Crystal System Crystal system: cubic Physical Properties Colour in hand specimen: colourless or white when pure, more typically orange or red due to inclusions of iron compounds, and may also be grey,…

Formula Fe2O3 Structure Non-silicate Crystal System Crystal system: trigonal (-) Physical Properties Colour in hand specimen: black, steel-grey and bright to dull red Streak: cherry-red Cleavage: none Hardness: 5-6 Optical…

Have a look at the alkali basalt (L100), the porphyritic rhyolite (L110) and the garnet schist (L504) in the 1A Reference Series.