6. Investments

The Company considers all highly liquid investments with a maturity of three months or less when purchased to be cash equivalents. Short-term investments include investments with maturities greater than three months, but not exceeding 12 months, or highly liquid investments with maturities greater than 12 months that the Company intends to liquidate during the next 12 months for working capital needs.

The Company determines the appropriate classification of its investments in equity securities at the time of purchase and re-evaluates those classifications at each balance sheet date. Available for sale investments are marked to market at each reporting period with changes in fair value recorded as a component of other comprehensive income (loss). If declines in fair value are deemed other than temporary, a charge is made to net income (loss) for the period.

The following tables summarize the Company’s investments:

December 31, 2012	Cost		Estimated Fair Value		Carrying Value
Investments:
Short-term:
Warrant to purchase common stock	$	124	$	—	$	—
Available for sale common stock	$	207	$	242	$	242
Total available for sale	331		242		242
Total short term	$	331	$	242	$	242

The Company did not hold any investments at June 30, 2013. The available for sale common stock at December 31, 2012 consisted of 3.0 million shares of a junior mining company received during the third quarter 2012 related to the 2011 sale of the Company’s Paca Pulacayo property in Bolivia. During the first quarter 2013 all of the shares were sold for net proceeds of approximately $0.2 million resulting in a nominal loss recorded to interest and other expense.

At December 31, 2012 the Company held warrants to purchase common stock of a junior mining company which were acquired in a transaction related to the Company’s exploration activities. At December 31, 2012 the warrants had a nominal carrying value of less than one thousand dollars. The warrants expired on January 6, 2013 and the Company recorded a realized loss of approximately $0.1 million to interest and other expense.

Quoted market prices at December 31, 2012 were used to determine the fair values of the above investments. See Note 14 for further discussion on the fair value measurement techniques used by the Company to value the above investments.