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LOT 2392
Manganese Dendrite Landscape Plaque Group
4 1/4 x 2 3/4 - 3 7/8 x 3 in. (410 grams total, 10.9 x 7 - 9.7 x 7.6 cm).
A group of three sawn rectangular shale specimens, each displaying manganese oxide dendrites resembling ferns and branching vegetation. [3, No Reserve]
ProvenanceEx Mineral Imports, London, UK.
Gregory, Bottley & Lloyd (Gregory's), Harwich, UK.
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AUCTIONS:
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Large Iridescent Placenticeras Ammonite from Alberta
Bear Paw Formation, Upper Cretaceous Period, circa 76-73 million years B.P.Sold for (Inc. bp): £5,980
Placenticeras costatum with gem quality fossilised shell with some visible suture lines, conserved and stabilised with natural polish and acrylic lacquer, with excellent iridescence showing red, green, orange and gold colours. 952 grams, 26 cm
Found St Mary River Valley, Lethbridge Mining District, Alberta, Canada. Property of a Bristol, UK, gentleman collector. Accompanied by a certificate of authenticity, exportable under Moveable Cultural Property Permit no.7021-25-12-22-0102.
The striking iridescence of these ammonites from Alberta, Canada, termed 'ammolite', was given the status of a gemstone by CIBJO in 1981. An iridescent opal-like play of colour is shown in fine specimens, and is caused by the microstructure of aragonite, the same mineral contained in pearls and nacre. The thicker the structural layers, the more reds and greens are produced; the thinner the layers, the more blues and violets predominate. The ammonites are a group of molluscs that lived in the seas from the mid-Devonian (approximately 400 million years ago) to the end of the Cretaceous (65 million years ago). The sequence of events that famously killed off the dinosaurs also drove the ammonites to extinction. -
![Group of Ten [10] Cut and Polished Agate Geode Slices](https://timelineauctions.com/upload/images/items/small/256014-s.jpg)
Group of Ten [10] Cut and Polished Agate Geode Slices
Sold for (Inc. bp): £78
Comprising ten polished slices showing contrasting banding, six in enhanced green colour. 1.08 kg total, 10.5-13.3 cm
From Brazil. Ex Mineral Imports, London, UK. Gregory, Bottley & Lloyd (Gregory's), Harwich, UK. -
White Quartz Geode Slice with Amethyst Core
Circa 140-120 million years B.P.Estimate: £800 - 1,000 (+bp*)
Opening Bid: £440
Cut and polished slice showing dense intergrown layer of white quartz crystals, the centre with groups of small lavender-coloured amethyst crystals; mounted on a custom-made display stand. 4.54 kg, 34 x 25 x 2cm, 52 cm including stand
From Artigas, Uruguay. Property of a London lady.
