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Oco geodes are mined in northern Rio Grande do Sul province in Brazil.  These geodes are quite popular given their smaller shape, thin skins, and wonderful agate in the shell with drusy quartz interiors.  Many of these geodes also contain goethite crystals (or another related iron mineral).  These geodes are approximately 138-127 million years old and are surface mined from outcrops in the Tres Pinheiros region of Rio Grande do Sul.  Most Ocos are between 1-3 inches in diameter although some larger and smaller are also occasionally available.  These geodes typically have a variable thickness agate shell with a fine drusy quartz lining of various colors from clear to light brown or smoky quartz most common.  Some amethystine varieties are also encountered in approximately 5-10% of these geodes with the color varying from a light lavender to a dark smoky amethyst.  All of our Oco geodes are imported directly from the mine owner in Brazil - the geodes were high-graded on site in terms of their hollowness and many of these geodes are considered "casa fina" (the most hollow geodes).  All of our Oco geodes are guaranteed at least 90% hollow by volume, meaning at least 9 out of 10 will contain an open, crystal lined cavity.  Please note on a few specimens, especially those where cracks were not detected, some dirt or rust may be present on the quartz lining.  Such substances can be washed out of the geode once opened.  Information source - "Geodes, Nature's Treasures" by Cross/Zeitner (2006) and Geode Gallery's supplier in Brazil.

IMPORTANT NOTE ON OPENING OCO GEODES:  Given the agate skins in these geodes, it is strongly recommended that these geodes be cut open versus cracked open especially if you want to polish the agate shell.  They do take a very good polish when cut open and are among the most popular geode varieties to cut and polish given their banding and ability to take a good polish.  The majority of these geodes are cut and polished on-site in Brazil - see our Opened Brazilian Oco Geodes page for already cut/polished Oco geode pairs.

Simple Shipping:  In the United States, all orders over $100 receive free shipping!  Order subtotal $5 or less = $4.00 shipping; $5.01-$20.00 = $6.95 shipping; $20.01-$60.00 = $9.95 shipping, $60.01-$99.99 = $13.60 shipping, and all orders $100 or more ship for FREE!  International orders please contact us or use our secure shopping cart for your shipping costs.  If you do not want to order online through our secure shopping cart, please call or text Mike at (309) 335-6740 between 9am-5pm Central M-F.  If I cannot answer, please leave a voicemail with your name, return phone number, and a message that you would like to place an order over the phone.  I will return your call as soon as I am able, thank you!

OCO 175
OCO 175

1.75 x 1.75 x 1.75 in (cm?)

$ 5.00


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WOCO 01
WOCO 01

2.6 x 1.8 x 1.5 in (cm?)

$ 8.00


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WOCO 03
WOCO 03

2.75 x 1.75 x 1 in (cm?)

$ 6.00


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WOCO 06
WOCO 06

3.1 x 2.25 x 1.5 in (cm?)

$ 11.00


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WOCO 07
WOCO 07

2.5 x 2.25 x 1.25 in (cm?)

$ 5.00


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WOCO 08
WOCO 08

3.3 x 2.6 x 2.25 in (cm?)

$ 26.00


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WOCO 10
WOCO 10

2.6 x 2 x 1.3 in (cm?)

$ 8.00


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WOCO 11
WOCO 11

3.1 x 1.9 x 1.6 in (cm?)

$ 8.00


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WOCO 12
WOCO 12

2.3 x 2.25 x 1.4 in (cm?)

$ 8.00


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WOCO 13
WOCO 13

3.25 x 2.3 x 2.5 in (cm?)

$ 18.00


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WOCO 14
WOCO 14

2.75 x 2.1 x 1.75 in (cm?)

$ 11.00


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WOCO 15
WOCO 15

3 x 2.6 x 1.6 in (cm?)

$ 9.00


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WOCO 16
WOCO 16

2.75 x 1.75 x 1.5 in (cm?)

$ 5.00


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WOCO 18
WOCO 18

3.25 x 2.8 x 2.3 in (cm?)

$ 21.00


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WOCO 19
WOCO 19

2.25 x 1.8 x 1.5 in (cm?)

$ 6.00


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WOCO 20
WOCO 20

2.3 x 2.2 x 1.75 in (cm?)

$ 8.00


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WOCO 21
WOCO 21

3 x 2.7 x 1.7 in (cm?)

$ 12.00


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WOCO 22
WOCO 22

2.9 x 2.1 x 1.3 in (cm?)

$ 11.00


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WOCO 23
WOCO 23

2.25 x 2 x 1.5 in (cm?)

$ 6.00


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WOCO 24
WOCO 24

3.6 x 2.7 x 1.6 in (cm?)

$ 17.00


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