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Drawings #2

Written by Maddy Saturday, October 12, 2019

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Some of my first successful tries for drawing animals, hope you like them

Drawings

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Cerussite

A specimen of cerussite from Maroc Cerussite is a Lead Carbonate and an important lead ore. The name comes from latin cerussa, means white lead. Cerussite is isomorphous with aragonite. Like aragonite, it is very frequently twinned (occurs when two separate crystals share some of the crystal lattice points in a symmetrical manner). Three crystals are usually twinned together on two faces of the prism, producing six-rayed stellate groups with the individual crystal intercrossing at angle of nearly 60 degree. Usually is colorless or white, sometimes grey or greenish from transparent to translucent and adamantine luster. Cerussite from certain locations is rich in silver and may be used as minor silver ore. Uses: lead plaints, lead source and cosmetics throughout history Characteristics Group Carbonate - Lead Carbonate Formula PbCO 3 Variable formula: (Pb,Ag,Cr)CO 3 Lead 77,54%; Carbon 4,49%; Oxygen 17,96% Crystal system Orthorhombic Color: white, colorless, gr

Wollastonite

Wollastonite from Brazil Wollastonite is a calcium inosilicate mineral that may contain small amounts of iron, magnesium and manganese substituting for calcium. It is usually white. It forms when impure limestone or dolomite is subjected to high temperature and pressure and sometimes occurs in the presence of silica bearing fluids as in skarns or in contact with metamorphic rocks. Has acicular nature. Properties: high brightness and white coloration, low moisture and oil absorption, low volatile content. Uses: Primarily in ceramics, friction products, paint filter, plastics, cement, flux for welding. Characteristics: Category Inosilicate mineral ; Calcium silicate Formula CaSiO 3 Calcium 34,50%; Silicon 24,18%; Oxygen 41,32% Crystal system Triclinic Color: white, colorless, gray Habit: rare as tabular crystals, commonly massive in lamellar, radiating Cleavage perfect in two directions at near 90 degree angle Hardness: 4,5-5 Fracture splintery to uneven

Labradorite , Albite , Spectrolite , Anorthite

Labradorite from Australia Labradorite is a feldspar mineral in the category tectosilicate. It has an anorthite percentage (%An) of between 50 to 70%; Anorthite is the calcium endmember of the plagioclase feldspar mineral with the formula of pure anorthite CaAl 2 Si 2 O 8 ; found in mafic igneous rocks; a rare mineral on Earth but abundant on the Moon. Twinning is common. Labradorite displays an iridescent optical effect or schiller known as labradorescence making the mineral glow with yellow, green and blue by rotating it in different angles. The cause of this optical phenomenon is phase exolution lamellar structure, occurring in the Boggild miscibility gap. Effect visible when the lamellar separation is between 128 and 252 nm, the lamellae are not necessarily parallel; and the lamellar structure is found to lack long range order. The lamellar separation only occurs in plagioclases of a certain composition in particular, those of calcic labradorite and bytownite

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Drawings #2

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