(Adds CFO comment, details; updates shares)     By Abhirup Roy and Subrat Patnaik     July 29 (Reuters) - Corning Inc  
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    reported second-quarter core earnings below analysts' average estimate, hurt by lower demand for its Gorilla Glass, which is used in smartphones made by Apple Inc  
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    and Samsung Electronics Co Ltd  
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   .     Corning shares fell more than 10 percent in early trade on the New York Stock Exchange.     Gorilla glass sales fell due to lower demand for smartphones and tablets and a delay in the launch of certain new products, Corning's senior vice president, Tony Tripeny, told Reuters.     Corning also cut its full-year growth forecast for cover glass shipments to 20 percent on lower demand for tablets and touch notebooks, Chief Financial Officer James Flaws said on a conference call.     Samsung, one of Corning's biggest customers, reported weak handset sales in the second quarter, as it faced slowing market growth and intensifying price competition.  
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        Apple is also reportedly planning to switch from using Gorilla glass to GT Advanced Technologies'  
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    Sapphire glass for its next iPhone.     Shares of GT Advanced Technologies have more than tripled in the past year, while Corning's shares have gained 43 percent.     Corning has also been hurt by falling prices of LCD glass over the past few quarters, but said it expected LCD glass prices to fall at a slower pace in the current quarter.     "In the third quarter, it (LCD glass price) is returning to the rate it was for most of 2013," Tripeny said.     The company reported a rise in quarterly core net sales, helped by higher demand for TVs in the run-up to the FIFA World Cup.     Core sales from Corning's display technologies business, which makes LCD panels for Sony Corp  
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   , LG and Lenovo Group  
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   , and accounts for more than 25 percent of the company's revenue, grew 62 percent.     The company posted core net sales of $2.58 billion on core earnings of 37 cents per share, missing the analysts' average estimate of a profit of 38 cents per share, according to Thomson Reuters I/B/E/S.     The company's net income fell to $169 million, or 11 cents per share, in the second quarter, from $638 million, or 43 cents per share, a year earlier.  
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        Corning's shares were down 9.4 percent at 19.98 in early trade on Tuesday.          (Editing by Simon Jennings)  ((abhirup.roy@thomsonreuters.com)(within U.S. +1 646 223 8780, outside U.S. +91 80 6749 6378)(Reuters Messaging: abhirup.roy.thomsonreuters.com@reuters.net))  Keywords: CORNING RESULTS